I've always been obsessed with an idea to have it on the account I currently play without having to find someone to recruit.
If you want to do the same thing, you should:
- Make sure both Battle.net accounts belong to you. Let's say Account A is the account with the desired mount, and Account B is the destination account.
- Level a character to level 20 on Account A (since you're able to play up to level 20 without having to subscribe)
- Learn the riding skill and mount up using the desirable mount (Obsidian Nightwing, Zhevra, X-53 Touring Rocket or such)
- Log out while mounted.
- Contact Battle.net support (I did it with Live Chat) and ask to have your WoW account moved under a different Battle.net license (Account B)
- When done, log into Account B with the character you leveled and mounted up with.