When it comes to enmity between elves and deep elves, imaginations is a bit constrained.
It's a game rule that Elves and Deep Elves have a hatred so deep, so profound, that were SK a sci-fi world we would have identified a Gene for it. The kind of gene that once removed, it turns an elf or delf into a half-elf
Beyond that, it is perfectly acceptable to be civil towards your enemy. Hating the very essence of another race doesn't necessarily mean acting all stupid about it. But, in suzie's example I'd much rather charm -any- other race to have around as my charmie, than a Deep Elf. Just being next to one should take a great effort from the character not to lunge at their throat.
Consider it a sort of uhm... bikini wrestling. Only without the mud and the women, but with frail aloof fey creatures instead.
*nods*
As for imagination, it's fine and well as long as it's done within the confines given to you by your game master, which in this case is the immstaff and the help files they've written on how some things should be acted out.
Sorry if it sounds all negative to you, but the concepts of evil elves, or neutral deep elves (imagine, not good, but neutrals!) is a dead horse that has been beat up so badly, there's not any skin left.