His ears were up because he was actually trying to nuzzle Pip down her backside. His ears tend to flop up and down, depending on what he’s doing at the moment.
They just stayed there, they’d gotten into the box by themselves. At one point, before Pip decided to leave the box, Mimzy was trying to get his head under her flank so he could hide. (he ducked his head down into the submissive pose and just waited for her to come closer)
There has been no aggressive behavior between them in the whole six days that we’ve been doing this. And I think the last time they were together, one tried to groom the other and ran a few licks down the nose. (I think it was Pip who tried to groom Mimzy, but I don’t remember.)

When I put Mimzy back in his pen tonight, he seemed decidedly put out. I think he wanted to stay in the xpen with her.
I guess I just want to know what to look for, so that I make sure they stay together at the right time. I don’t want to confuse them.

EDIT: Oh, and btw, if Pip seems a little wild-eyed in this pic…well she always looks like that. I’ve seen the whites of her eyes when all she’s doing is oggling a carrot coming her way. 0.o She’s our little ‘psycho-bunny’.

Well today Mimzy looks quite fine with being in his habitat…he seems a little off again, so we’ve just let Pip into the xpen to see if she can get her willies out. (Hopefully she’ll sleep better tonight!)
I’ll have to try the sleepover soon, but until I am sure they won’t be nipping each other I think adult supervision is required. ^^
Although I do hope that Mimzy’s ‘off’ attitude isn’t due to being separated from Pip. AT this point, it’s hard to tell, since he’s also being kind of fussy about his eating habits. That delicate balance of bunny emotions seems to be almost impossible to level off sometimes.