If I am in hero form, have just exhausted my hero to defend against the villain attack and draw my obligation card during the encounter card step, can I flip to alter ego and discard the obligation or do I have to be readied? Thanks for any replies.

Pretty much all of the Obligation cards so far function the same:

1. They give you the option to flip to Alter-Ego form if you so desire.
2. They give you the option to Exhaust in Alter-Ego form to remove the card for the rest of the game. This only works if you are readied, so defending does leave you vulnerable to your obligation cards because:
3. If you are unable or do not wish to flip to Alter-Ego and Exhaust, there is a negative effect for your hero. This cost is paid and the Obligation is discarded (but the possibility remains that it will pop back up again.)

Thank you.