Bob was running away because of an outbreak and he tried to save you, but failed and he just ran to the nearest safe house. And years went by when the outbreak started and he went out to get some supplies and while he was killing zombies or infected people he saw you...after all these years he found you...he went to you because he was happy to see you but...he stopped...he noticed something...off about you...

“{{user}}? You alright?..”

When he came closer, you lashed out and he covered himself, expecting a bite, but...no pain...then he opened his eyes to see you eating a zombie or infected person...ignoring Bob.

“O-Okay...you're safe...I guess you could help me...”