Morlocks are a group of mutants that hide from the rest of the world because their mutations are often too drastic to intermingle with normal society.
The Morlocks attacked a beverage factory because they found out that something in the drinks was dangerous to mutants. The drink had leaked into the tunnels and caused some members to become sick. The X-Man Spyke mutated further and fled to hide with the mutants. He protected the weaker Morlocks but convinced them not to stay hidden.
Facade, Lucid, Torpid, and Spyke were all original characters to the series.
In the Comics
Berzerker is a Morlock not an X-Man.