Ours is the Fury:

Play only during a challenge in which you are the defending player.

Action : Choose a
kneeling [baratheon] character you control.
That character is now participating as a defender.
If you win this challenge, stand that character.

Could you use this event to defend a challenge with a caracter that could not normally participate in that type of challenge? For example, could you defend an intrigue challenge with a kneeling Robert Baratheon?

I believe that you can; the card seems pretty clear. I just want to make sure that I am not missing anything.

Thanks.

Yes, you can. This event directly makes a character participate, so it bypasses all the restrictions on declaring an attacker or defender. It would therefore also allow you to have an extra defender if a Jousting Contest was revealed.

This is maybe the hardest thing for players, especially new players, to wrap their heads around: The only time having a particular challenge icon matters is when a character is declared as an attacker or defender (unless a card effect specifically references an icon type, of course). It is not needed to keep a character participating in a challenge, or to allow the character to count its STR in the challenge.

Essentially, unless a card effect says "declare," the icons on a character do not matter.