Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-14066471-20140114172238/@comment-24398707-20140121225858

Derek chose Isaac, Erica and Boyd to be betas in his pack because they were easy to convince and he was in a hurry to build up a pack because the alpha pack was coming. An alpha only needs 3 betas to have an official pack, and an alpha is stronger with a pack because there is strength in numbers, so the more werewolves there are in the pack, the stronger the pack as a whole and everyone in it gets. Derek could of chose anyone to turn, but he doesn't force the bite on people and other people would not have been as easy to convince. An alpha gains a beta's full power for their own when they kill their betas in their pack. Getting a beta to join your pack gives the pack power as a whole which includes everyone in it. The alpha pack members all killed their entire packs which all included more than 3, which is why they were so powerful and Derek seemed so weak compared to them. Plus the alpha pack had 5 alpha's in it, which also added to their power.