The other reason is you

Go save the world, son

N - your chat noir
Adrien responded with a sheepish smile
A - I
Gabriel got up at once and grabbed his sons hand.
G - I- my own son, Chat noir? I suspected it but I didn't, Oh Adrien I am so sorry.
A - I know and I forgive you, both of you
Plagg flew out his pocket
P - May I remind you we have a villain to defeat!
A - Plagg, claws...
G - no!
A / N / P - what?
G - it's too dangerous Adrien, I can't -
A - father! You forget while you were Hawkmoth for a year I was the cat battling alongside Ladybug.
N - Gabriel, let him go, they've never lost against you and he won't this time
G - but what if -
N - Go Adrien, I'll look after your father
Nathalie placed her arm around Gabriel brining her other hand to his chin pulling his head till he looked at her
N - he will be okay
There was so much honesty in Nathalie's words that Gabriel had no choice but to believe it to be true.
Adrien had transformed but before he could leave Gabriel grabbed a hold of his arm.
G - go save the world, son.