What happens when it all goes to hell? When your best friend isn't? Let's find out. Friendships are a funny thing. They can vacillate. They can also stay true. In team building, they can be solidified. They can be gelled. However, when the chips are down, enemies can become friends and vice versa. In this fourth episode of Yellowjackets (Showtime) titled "Bear Down", we're shown that…