In The Invisible Man, betrayal is always tied up with priorities. Let us explain: the Invisible Man doesn't steal from his dad just to be mean. He steals because he cares more about his scientific experiments than anything else (including his family). On the same token, we expect someone to keep their friend's secrets, but when Griffin outlines his supervillain plan to take over England, Kemp decides that he has a more important priority than loyalty to his friend: protecting his country and neighbors. So whenever we see a betrayal – whether of another character or of a principle – we have to ask: what does this show us about the betrayer's priorities?
The characters in The Invisible Man betray each other out of pure selfishness.
Betrayal is evenly distributed among the characters in The Invisible Man to remind us that we're all potential betrayers.