I have Coldhands in play and know that my oponent will be playing Valaar

I reveal the plot "called to court" - this gives me inititive

When revealed, each player may put an in-House character of printed cost 3 or lower into play from his or her hand. Each player must choose 1 character he or she controls and return it to its owner's hand, if able.

Ideally I would like to return Coldhands to my hand, puttng the characters who were removed from play back into play and for those characters to be killed for VM

As CTC is my plot card, I return Coldhands to my hand before my oppponents get to put in / take out a character ...

Does Coldhands response come after all players have done CTC?

Does Coldhands response come before other "when revelead" - i.e. VM?

Your resolution of CTC is a little off. All players (starting with the person who played it) puts a character into play if they want. Then, all players (starting with the person who played it) returns a character to hand. They are separate effects, so you resolve them separately.

You are not dealing with Coldhands' Response because he is not coming into play. You are dealing with the "return to play" effect that is initiated passively when he leaves play.

The order of the plot reveal is ALWAYS:

1. Reveal plots

2. Count initiative

3. Determine First Player

4. Resolve all "when revealed" plots

5. Passives to 1-4

6. Responses to 1-5

CTC and Valar both resolve in what I've listed as #4 above. The "return to play" passive effect from Coldhands leaving play doesn't happen until #5. The removed characters return to play after Valar has resolved. There is no choice a First Player can make in this scenario that will change that.

Thanks - for CTC we were going round the table with each player putting a character in and taking one out

What if I brought back Joffrey as a result of Coldhands leaving play

Assuming 3 lords / ladies were killed for Valaar, Joffrey would enter play in step 5, so he would be able to trigger his response in step 6 and claim 3 power?

Response: After a Lord or Lady character is killed, Joffrey Baratheon claims 1 power. (Limit 3 times per round.)

Correct.