I refuse to believe Asriel and Dess had a thing. Asriel is such a giga faggot that it doesn't surprise me Ralsei is straight up a copy of his personality. He is a bottom.
At most Dess probably pegged him or messed around with him, but she is still a woman in the end and craves a dominant man. Even if she has something with Asriel, he would just be a woman on her eyes.
Noelle craves for a masculine figure too and no wonder Carol is like that when her faggot dying husband is secretly sleeping with the owner of the flower shop.
Fuck you Asriel, I hate you, because I love Flowey. Flowey is cool as fuck and I hate to see that every Flowey fan in existence is always a Asriel fag too.