haha AUUGHHHHGH so much is unknown, so this will be my vague impressions based on what we do know about either's small comments! followed by DELUSION.

Asriel was so innately accommodating to Kris, I have to believe he was considerate of Noelle's paranoia & sensitivity! If Asriel is keyed into signs of anxiety, I think for the entire group (Kris, Noelle, Dess...) he may have offered solutions catered to whoever, whenever needed.

In Noelle's memory of the night exploring behind the graveyard, she takes care to remember not only Dess's wiping her tears, but the "warm sleeves that smelled like cinnamon", Azzy's jacket.

M-maybe the ICE-E story from the ARG conveys something well... (it is written by a young Noelle)
**"Story UPDATE!!!!!!!!!!

My sister burned the box in the grass to kill it and it smeld like charcle pizza

she burned out ice-e eyes and he looked EVIL and azzy said took it and said we should berry the box and kris duged a whole in the ground in the greive yard and I was so scared a zombie woud come up and i tried to say kris I’m scared and they turned around with the box over there face and I screemed so dess hitted them and took it away and through it away and i think its going to come kill me"**

...you can see how at times, Dess is not as helpful to Noelle as even she'd probably prefer to be, and Asriel is here to offer a more peaceful solution for Noelle's anxiety... while still thinking whimsically enough to bury a pizza box, lol. This kind of solution is sweeter than a purely logical and pragmatic parental one, I like that it still engages in her magical thinking.

I-I think that sort of 'prince charming' thing... is entirely possible... I feel embarrassed to discuss it, but... yeah...!

We see identical trophies in Azzy and Elly's rooms, but Asriel's are gold while hers are silver... a medal in the darkworld is described as being from a 'legend athlete', and Noelle says it belongs to Asriel! They likely were respectively 1st & 2nd place (I wonder if anyone else was even IN Cross Country at that time?).
He also had a beautiful voice in choir, contrasting to young Noelle, who states to have been so bad at singing that Kris would cover their ears...
I wouldn't be surprised if Asriel was a key reason Noelle could participate in things like Cross Country, and Choir... or going further, if she chose those vocations in order to be around him more often. Especially after Dess is gone.

I also think being around Asriel would temper fear of Kris for her, as Asriel of course loved and cared for Kris, and Kris loved Azzy. It would be easy to understand, "Kris isn't actually that bad, or Azzy wouldn't love them so much".

The cinnamon-scented sleeves and Ralsei's traits convince me Asriel was also a baker, I'd like to think he would bake treats for all of them, and have a few in his pocket for emergency consolation. An older boy pulling a cinnamon cookie from his backpack while you're crying, because you tripped at the finish line of your race... he could have a unique grace to him. If Noelle grows up to be the sort of person... always stocked with extra pencils for Kris, gifting them peppermint cookies, I would assume she 'got that' from Asriel.

I kind of think of a funny chain of effect, where ...
Asriel was there for Noelle when Dess disappeared, taking on an older brother role for her,
and then, when Asriel goes to college, Noelle tries to do for Kris what Azzy did for her-- a sort of older sister role for Kris (though I doubt she could articulate it as that herself).
She could plainly see Kris freezing up & lost, think of herself, & think of how much what Azzy did meant to her. It isn't only what Kris needs, but it is also what Asriel would want, isn't it? It's a favor to Asriel as much as Kris.

All of these qualities... of someone older, kind, soft-voiced, talented in things she would like to be good with...
I think Asriel could have been more of a role-model for Noelle than Dess was... Not to dismiss Dess's incredible value to Noelle-- but I doubt Noelle necessarily wanted to 'be that' for others! Maybe there were even times she longed to be able to provide more comfort to Dess, a troubled girl denting dozens of instruments, suffering nightmares...

There are many similarities between Noelle & Azzy, and I don't chalk it up to coincidence... but a willful cultivation, imitation, admiration, on Noelle's part. And Asriel's....?

I'm always kind of transfixed on Ralsei's response to the "Noelle tea"...
It's soft and sweet.
in my opinion his response to Kris & Susie tea are artificial (describes simply blueberry & grape), because he can't uh, reveal his vast depth of knowledge to either of them at that time (prophey...). But for whatever reason, even though it makes no sense for 'his character' at this point in the narrative (after all, Noelle and Ralsei hardly interact at all-- the Ralsei tea is completely empty for Noelle, because she doesn't "know" him), he describes the Noelle tea beautifully. A tasteful peek into Asriel's feelings towards Noelle?

AS FOR THE REST OF THIS QUESTION!!!

(at the moment, I think of group playing as entirely AU timeline stuff, forking off from childhood, the sort of thing that would derail the entire timeline as we know it... I worry Azzy growing up only ever felt he could 'let go' enough to 'play' around Kris, at home, HENCE having such a controlled and mundane life, trapped in generic college pipeline... but in an ideal world, where things went a little differently, Kris could have pulled Azzy into joining group play!!! I'm not sure the canon Azzy got to express himself so freely... sooner ah, hiding behind anonymized agents like a faux spam e-mail lol)

Laughing at "good cop bad cop", this is not a bad way to put it at all. It's especially apt because while I think Asriel tries to support or accommodate Noelle, uhm do damage control for Young Kris Madness, his ultimate uhm... 'objective'... is still to enable whatever Kris wants, LOL. The Good Cop is still a cop and both ultimately want you to, follow the same order. One is just better at presenting the objective. The ILLUSION of choice.

To put it into practice, you can imagine the White Mage captured by the King of Card Kingdom... Jevil being crazy, frees her, but also instigates a lot of chaos and difficulty (also, Kris plays the King who imprisoned her in the first place)... Seam (Asriel) can intervene and offer her escape in underhanded, subdued methods, using his magic, without drawing undue attention. Seam is a little mysterious, but calm, explains to the Mage her options, risks, possible outcomes, what they can do, and I think would offer her much more agency in decision-making (being interested IN those decisions, regardless of where the outcome may place them) (while Jevil would corner her into make-or-break altercations that force her to react immediately, fight for her freedom or submit to the King's pawns) (... but as you can see, both ultimately are 'interested' in her 'reaction'... making their goals compatible)... though Jevil and Seam both crave excitement, and they both like to play. Despite his 'better nature', Seam is drawn into Jevil's energy and ability to utterly upend status quo (if you think about it, this is what someone like Kris does for someone like Asriel).

Noelle may be a fearful person, but she's also curious, playful, and tempted by the allure of frightening things. Jevil isn't a tormentor, and one learns that he can be bopped without repercussion, lol. He is 'crazy' but he's not 'bad'. She can understand why Seam needs Jevil... a mage who would only perform duties, under court's orders, given no intervention. She isn't so different!

One can imagine Seam 'training' the White Mage in accessing her Ice Powers, while Jevil forces her into situations to truly use those powers, to access the intensity and purpose necessary to force it from her. The White Mage could freeze the King (also Kris), and Seam would be forced to help as the entire kingdom comes rushing at them!

^ this is all what 'leads' to my drawing of Seam, Jevil, & the White Mage 'escaped' into the woods... Asriel playing with Kris and Noelle more passively, lightly, at first (voice quiet, gestures small, in the privacy of their bedroom... scared of a parent coming home, overhearing, scolding or asking questions)... doing little more than an NPC, only seeking to enable whatever Kris and Noelle are doing.... but suddenly, he is swept into the shocking narrative, astounded by Noelle's decision to upend the entire kingdom-- an act which severs Seam from his post, the structure of their life. If there is no King to answer to, what does Seam act for? If the Kingdom falls, what does its mage do? <- symbolic itself for Asriel, who is bound to obligations as a 'responsible older brother', or the one who must always 'know better' and 'set a good example'... what if we pretend to destroy the institution, lol.

In a fenzy of immersion, Seam grabs Jevil & the White Mage, casts a quick spell to temporarily pause time, and sails them all out a window... (for real though, Asriel suddenly ushers them all through the window of their bedroom, an act which would make Kris feel like, YES YES YES YES YES!!! YES YES!!!! AUGUGHRHGG!!!!! YES ASRIEL!!!! THIS IS THE BEST EVERRR LETS GO LETS GO!!!)

... so you get the idea! One can imagine this with all sorts of scenarios, and I think the three can choose to 'reset' any RP, try it from another angle...
As for how she feels, getting to somehow 'access' Asriel as a playmate, would be a little humbling, I think! She would have to know it is rare, and even pick up on his shyness, hesitancy! The attention WOULD be exciting and fun, Kris would show new sides of their own personality, narratives, dynamics, the likes of which could shock her.

On a way less cerebral note I think Asriel's 'favorite' games to play with Kris privately were often like, uhm well Ralsei Rancher lol, catpetterz. We have evidence uh, both Kris and Azzy like to get a treat and be called good and pet and do tricks and walkies. So that sucks, and we have to live with it every day, no matter how painful it is. I could see a 'generous' Kris thinking it is doing Asriel a 'favor' to instigate a Ralsei Rancher RP. And Asriel would simply have to endure everyone pulling his bridle, petting his face, brushing him, riding him...

Must acknowledge Noelle enjoys Catpetterz and, AS FAR AS MY INSANE PERSONAL INTERPRETATION OF AMBIGUOUS EVENTS GOES, Asriel programmed mods that infected her game via Spam e-mails Noelle was gullible and kind enough to click. She cared kindly for her pipis, which leaves due to happiness. This makes you think. *stares into the sunset* but I don't expect anybody to 'go with me' on this. In this indirect and desperate way, Asriel managed to 'play' with Noelle in her silly, girly petsim. Like a SCREAM escaping a TOMB.

I sooner think of Kris & Noelle 'teasing' Asriel, half by accident, but I also think it could turn more mutually willful over time... it's in Kris's nature to tease and taunt Asriel in my opinion, a history of pushing his buttons, liking to rile a reaction out of his OCs (isn't it more fun if the horse kicks & bucks, and even more fun if it bites? it's so rare!! also, whatever tf Spamton & Tenna have, and Seam & Jevil... they like this kind of on-and-off-again playing-fighting-loving nonsense, IT'S SICKENING)... while Noelle, she's historically a pretty powerless person, but by that coin I think allured by a sense of power! If she caught on to Asriel flustering or 'reacting' to her, I could see her pushing a hoof to the gas pedal, haha... I mean, what WOULD a young Seam do, being flirted with, being invited to dance, being told they are cute or pretty, being brushed, being dressed in a ribbon? EVEN JEVIL DOES NOT KNOW THIS! Honestly, EVEN SEAM DOES NOT KNOW THIS!!! The Court Mage doesn't... attend the ball....! The thing about having a, little girlie girl in the room, is, she presents your OCs with situations you wouldn't naturally invent, amongst yourself, in your dumbassed "MAN COUNTRY".

I think Asriel and Kris are a LITTLE helpless to more insipid whims, even if they both ENJOY a romantic or sensual turn in MEDIA, secretly... they are like, stupid, programmed to create Spamton & Tenna dynamics, at best sortof 'dancing around' an idea of 'lovers', but quickly ESCAPE POD-ing into chicanery, nonsense, fighting.... (and unfortunately I'm sure Kris loves Hitting and Asriel loves Being Hit... your fate is to be Yoshi and Mario Throwing Yoshi Into Pit).

anyway... on the subject of Asriel being teased or what have you... it's difficult & painful to be indulged, and Asriel has the most guilt & weight on his shoulders as the 'older' one here who just isn't sure when to 'say no'... Kris is bold and Noelle is curious, the two could wind up giving Asriel a panic attack haha... there is definitely an 'event horizon' where Asriel would be forced to confront his degree of participation, of course he would have the burden of being the one who must say 'no' if something 'goes too far'. But could he? And would uh, Kris let him? Would Noelle? What if it isn't a matter of 'what Asriel truly wants' but 'what is right/wrong'? Would they really argue in favor of 'what is right/wrong' over 'what Asriel truly wants'? What if it's just a 'game', is Asriel 'wrong' to even see it as 'more than that'? Is the panic attack ITSELF dirty and gross to have? Why be so upset over a 'game'? It's pretend, isn't it? If Asriel is soooo concerned with 'getting in trouble', or an even more strange & abstract religious kind of guilt, what can Kris or Noelle say, do? I can't imagine they would want concede to his miserable guilt!!! Kris would become stubborn, maybe even agitated, while Noelle would by sympathetic... so you kind of weirdly have a Kris Bad Cop Noelle Good Cop suddenly shining a light upon Perpetrator Asriel. Except that like, they just want to know what you want.

Pressing my brain though, god it's endless, I have to stop at some point. It's easier for me to access Seam & Jevil as there is an easy 'role' for Noelle as a magic user, but what the FUCK would Spamton and Tenna do with her? Fight over her, Looney Tunes Nonsense eachother for her allegiance? I describe Tenna & Spamton as like if a Wile-E Coyote and an Elmer Fudd or something were interacting, 2 flops designed to never 'win', there is no Bugs Bunny or Tweetey getting the upperhand, they are Both Underdogs who Suck and Can't Win. Maybe Kris would do everything in their POWER to never RP Tenna with Noelle, like NO!!!!!!!!!!!! And to be fair Tenna is like, sycophantic, simpering, pathetic, submissive, beseeching, needs reassurance & praise, everything I think Kris struggles with real shame about, and would struggle to show Noelle. I see 'Jevil' as an 'easier' persona, by nature having no 'allegiance', so Kris doesn't have to really 'answer' to anything, can always fall back on, 'well it would be Fun or Funny, so Jevil did it'.... so you don't have to 'validate' like, why Jevil would kiss Noelle or Seam, He's a Crazy Guy. Tenna I do think you do more than a gameshow with that fool and it's like, We Have To Euthanize Him. We Have to Put Him In a Sack and Throw him Into The Creek. SHOOT HIM.

By that same coin I think Spamton, for Asriel, is an INHERENTLY!!! 'anonymized' entity and dropping the mask and misdirection that is typing e-mails and programming code, well I don't. Think he could do it. But uhm it would be interesting to think of Asriel's psychotic self e-mailing Noelle from the spam account in the night and Noelle finally getting to 'catch on' that this entity was... either Kris, or Asriel, the whole time (not sure if she could work out WHOMST on her own!!). Uhm but my mind goes a little insane thinking about an Asriel secretly communing with Noelle via e-mails. Does she tell ... them, about these e-mails, or, does she remain hush-hush, if the e-mails ask her to be?

all of that. And there are so many more layers to access it's honestly neverending. I think Kris Does like to be put in jail and talked down to, I mean. NIGHTMARE is so ...................... mmnnn horny. I do think it is an Asriel. It talks like Flowey. Kris likes to misbehave and be, punished. Kris likes to be teased. It's like level 100 to get to this point... as a child I think Kris is reluctant to cede much of anything to Noelle, a little bit 'basic' in that regard.... easily overstimulated and frightened of indulgence, I would imagine....
the Asriel and Kris alone who indulge things like this (probably only via the opaque shield of programming/scripting a ROMhack together... even more obtuse than e-mails) are , microdosing a psychotic break for the two of them. I'm still fighting for my life, groping the walls in the dark, on this subject. But it will be acknowledged. There is an aspect of 'switchery' to Kris/Asriel AND/OR Noelle/Kris which twists the entire world upon its head.