He wasn't even sure why he was in his quadrants. A lowblood like him should be happy right, but somehow, Tavros wasn't that happy and it made Eridan pissed beyond belief.
At first, Eridan only seeked Tavros out as a matesprit for just the sake of filling a quadrant and for the sheer fact of pissing of Vriska who had an odd relationship with the Taurus.
The seadweller didn't say anything to him at all, he just went right up to him, pushed him into a wall and began kissing him. Tavros squirmed and flailed about but quickly gave in when he realized Eridan was a bit stronger than him.
Tavros denied it since but it seemed when Eridan gave a glare or demanded more affection, he would obey. Sure, he felt bad for treating his fellow troll like a dog, but if anything, he was his dog. After a while though, Eridan's swollen feelings generally became redder and it started treating Tavros more lovingly.
He would cuddle with him, stroke his horns, whisper sweet nothings into his ear, yet Tavros never did anything of that himself. He never gave Eridan a hug or kiss unless forced into it, he didn't want anything further and Eridan was pissed. After all he did, Tavros should love him! Be grateful.
But when Eridan thought about during terrible things to his matesprit, he looked upon his lovers sleeping face, tinted softly by brown, his peace, his cuteness. He simply couldn't do it.
Surely though, Tavros could learn to love him. Anybody could learn anything, though love was a tricky subject.