I think you are a
I'm not very serious when I am rolled.
flippant - to flip is to roll, and flippant is not serious.
If memory serves me, I spread uncontrolled.
rampant - RAM is the memory.
If you see more of me, I'll be given more slack.
Pants (plural) as long trousers or slacks.
With her, I'm famously pink or black.
The movie character the pink panther, or an actual black panther
I was expecting against 101 before.
anticipant - anti is against and CI is 101.
On my own, I'm a greedy man wanting more.
pantalone - one of the principal characters from commedia dell'arte, with exceptional greed.
When I stole from a bank, I thought God was all,
Pantheist - identifies the universe with God, and heist is the bank-job.
With nothing behind me, the children will call.
Panto - or pantomime for a children's show.
Title: Not a Long-Winded Riddle
A short breath is not long-winded.