With Newt in the middle!
(please say I'm not the only one craving this?)

Bonus if it all starts with them (not quite reluctantly) teaming up to gradually seduce Newt because neither of them is getting anywhere on their own - Newt's just too oblivious - and then it evolves into poly

Extra Bonus for 4 or 5 times Newt just didn't get it and the 1 time he definitely got it