Glaurung said:
Other wise i still can play Tracker by Stand and Fight but cannot commit hi to the quest. But still can use him later for defend or attack.
This second line is the correct way to play this combo. You have to announce all questing characters and exhaust them at the beginning of the phase. You can play an event card like Stand and Fight to bring in the Tracker, but you cannot commit him to the quest because the 'commit characters' step of the phase is already done.