I heard somewhere that while grounded figures (excepting those w/ L/C or HSS) had to stop when they became adjacent to an opposing figure, fliers do not have to stop should they become adjacent to an opposing figure.

True, or False?

True. Flyers just fly over/past others. Non-flyers (except with lea-climb or feats) have to stop when they become adjacent to opposing figures.

can fliers go through an occupied square, when not soaring?

Badges, where are you getting your ruling? I ran into this at Origins, but it's not in the FAQ, Danger Room, nor Icons rule books. Both rule books say that all characters must stop when becoming adjacent to an opposing figure.

LOSH maybe?

Its always been the ruling, but give me a minute to find it.

Look it up if you want, but that's how its always been.

Edit: And no, you do not need to go soaring, move past a character, come down from soaring. You just fly straight by.

I found a link to the LOSH rule book. It says the same as Icons and Danger Room. "A Character" not "booted characters", "a character".

A character can move through a square
occupied by a friendly character, but it can’t
move through a square occupied by an
opposing character. A character must end its
movement if it enters a square adjacent to an
opposing character.

Sure enough, thanks!

It's also Page 18 of the LOSH rulebook, just to the left of Hawkman.

The bottom line is that this is a very old ruling based on unclear wording in the rulebook. The line used to justify this is:

"Flying characters may move through squares adjacent to and occupied by opposing characters."

[sarcasm]The "without stopping" part is apparently implied and only morons would miss it, thus no official clarification is needed, and you are an idiot for not just knowing this.....[/sarcasm]