I like Mokole's explanation. Mine would've been inconsistent writing, but Mokole noticed another thread.
But I don't agree with it, for the reasons cited; Heather -has- always been strong - she brought Alpha together, after all. Twice - once when she brought Mac to Parliament and Cody (and was then indirectly responsible for the team's formation) and once when she summoned them all to fight Tundra.
Remember her fighting off Delphine Courtney - "Other superhero wives and girlfriends may be content to play hostage..." ?
- Le Messor
"I bent my wookiee!"
- Ralph Wiggum