Kris' relationships with ALL of the Holidays are genuinely some of the best in game.
Kris × Noelle
I literally, literally CANNOT shut up about these two, all that they shared and all they wished they could share. The way they've understood each other in ways no-one else has ever done.
This isn't even about Weird Route/Side B Kriselle though those two are perfection in an entirely different way
Kris × Dess or just Kris AND Dess if you're boring (/j)
I do NOT mean this in the 'Oh she groomed them' way. In an alternate universe these two could be and would be peak. We KNOW they had a really close bond and imagining Kris finding / being told about DessKnight and helping her because they love her or they love each other is such perfect angst. Just please give the fanfiction "(K)nights in the Dark" a read if you're interested. It's the perfect characterisation for both Kris and Dess and how their relationship could and should come about.
It also fits the greater themes surrounding Kris and especially Chapter 5 to feel like a second choice compared to Asriel.
A childhood crush on the cool older girl next door, who is the one person to truly understand their feelings of othering and innate differences to others, later becoming requited feelings (or not) would fit "Krismas and Dess" so well.
[Personal headcanon: DESS came up with Krismas because it sounds like something you'd call a younger kid. While I'm a firm believer in young Noelle calling out to "Krismas" and using the nockname to death whenever we see them interact and whenever earnest feelings are involved she uses "Kris" not "Krismas"]
Kris & Carol
Especially in a scenario that includes both DessKnight and Kress this dynamic is perfect.
Workimg with her to save December while also making Carol feel bad for burdening Kris with so much yet at the same time having Kris be pushed to do all these things by Carol...
Genuinely S-Tier
Those are the best but even Kris and Rudy is great.
He's the father-in-law that never QUITE was, the uncle that is dying and the man whose daughter Kris tries to help/save and whose family they try to repair. All while feeling guilty over not having visited him and especially about keeping everything relating to the Roaring Conspiracy secret from him AND Noelle.
At the end of the day, I want (NEED) Kris Holiday to be a thing at some point in their life, they deserve it.