Well, invictus means "to conquer" which might be a touch better than relentless which, on it's down-side, might describe Hippy's first wife.
If there were only those to choices, I'd go with Invictus.
Which is a better youth soccer team name, Invictus or Relentless?
Invictus is a much better team name. It signifies the kind of culture that makes a champion
Invictus is a much better team name. It has a much deeper meaning that symbolizes the kind of culture a team should have.
Invictus