Can previous mouse enemies become friends?

Question
Hi there,
I have two mice, both male. First got Meep about a month and a half ago. He was the last one in the pet store, and seemed to be extremely shy, and didn't like us humans at all. We thought he was lonely, and would respond better to having a mouse friend, since mice are so social.
We got Narm a couple weeks ago, who is younger, from a different litter, and VERY social and friendly with us. We introduced the two on neutral ground, and masked their scents with vanilla. Meep attacked Narm, and drew blood.. twice. I'm very protective of Narm because he's small, and was obviously bullied in the store, so I got another cage set-up, and have kept them in separate cages, but the the cages are side-by-side on a shelf.
I wasn't sure about keeping them side by side at first, and now, they're very curious about each other.  Meep, the bigger, meaner mouse often climbs on the side of the cage next to Narm, and sprays all over the place on that side of his cage.  Narm will climb up on his cage when Meep does this, but isn't as aggressive. They both chew the bars a bit when facing each other. I've given them both toys, things to chew on, and anything I can to keep them entertained. I can take Narm out and play with him, and that often calms him down, but Meep only runs from us humans - we can't even so much as touch him.

Does this mean they want to be closer to each other? Will they be friendly?  I kind of want to try introducing them again, but not if it means Meep will attack and make Narm bleed again. Narm is still significantly smaller than Meep.  Or should I move the cages further apart?

Thank you for your help!

Answer
Hi Jackie,

While female mice are very social creatures, males are not.  In the wild they have to fight and compete with other males for territory and for females, and it is no different as pets.  Once two males have decided they are enemies, there is no changing their minds, and putting them together can end in death very quickly.

What you suggested about moving the cages further apart is an excellent idea - being near other males tends to put those boy mice on edge, so interactions with you will be stunted by that constant stress of living right next to a threat.  I think once you separate them and focus instead on one-on-one time with them, you will see a drastic improvement in their attitude toward you, even Meep, though it may take a little time and patience.

Please let me know if I can help out with anything else, and best of luck!
-Tam