This is a neat pic for Valentine's Day and a pairing that I didn't quite expect! You might have mentioned that they're LIs in their descriptions, but that was quite a while ago for me, so I could have just forgotten.
I love the contrast with the two. Poison is spiky, tough and a very intimidating force whereas Lillian is his opposite: tender, soft and kind. I know that kind of pairing concept has been done many times before, but hey, it's a working concept. If it ain't broke, don't fix it. Plus, I've always found that I enjoy pairings like that especially when the character possess physical traits that correspond to their personality, which they do here.
The expressions really speak to both characters' feelings. Poison looks confident while soft and tender whereas Lillian appears a bit nervous, but is willing to follow his lead and let him make the next move. This is a well thought out composition and the eye contact really brings out their feelings towards each other.
My one grip with it is Poison's left hand. I'm not quite sure what it's doing, but hear me out. From where his wrist is, it looks like he's got his hand on her shoulder. But from the other end, it looks like his hand is cupping her armpit. Because of this, it's produced this awkward appearance of his left hand and has made it look like Poison's hand is literally going through Lillian's shoulder.
Overall, a great composition that shows the emotions between these two characters with only a slight technical issue.