frantic world

And there’s Greg, my rock in a frantic world. He’s always there to act as a steadying influence or as a reckless and impulsive character; fun yet practical, outrageous yet sober, dependable yet irresponsible and above all, always supportive. Would it all change?

And also what is a steadying influence?

Yes. All of those.

He's your rock because he is stable and more or less unchanging. Exactly the opposite of 'frantic'.

frantic conversationally can mean overly busy

other connotations could be inferred by any surrounding text