Mounts can be shared between characters on the same account login by placing the mount in the Shared Bank.
All items that are on a character or in that character's bank will be deleted when the Wizard is deleted. If you want to keep items from a character you are deleting, place those items in the Shared Bank before you delete!
I bought 2 mounts and one cannot be added to shared bank. The black panther will not add to shared bank. It is not full and my other mount (black Pegasus) shares just fine. I bought it because I read they could be shared but now I cannot share one. Why is this one un-shareable then?