Freshly ripped from the Vortex, and viciously channeled through the nightmare realms of Togarini and Malkuth, I bring to you:
Helping
When you support or assist another player character’s Move, explain how you do it and roll +Attribute, where the Attribute may or may not be the same that the helped player is using.
15+ Your assistance allows the other PC to increase the result of their roll by one tier (fail → partial → success). If they already rolled a full success, the GM may at her discretion allow them to pick one more question, edge, or option than normal.
10-14 You face a hard choice of how deeply to invest yourself in helping your fellow PC. Choose 1:
- Increase their result by one tier, but suffer a cost or complication for it.
- Your help remains inefficient and adds nothing to their result.
-9 This went wrong badly. Choose 1:
- Reduce the other character’s result by one tier.
- Hurt yourself or get in trouble in the course of your supporting actions. The GM makes a Move against you.
Hindering
15+ Your interference forces the other PC to reduce the result of their roll by one tier (success → partial → fail). If they already rolled a fail result, the GM may at her discretion make a harder Move on the character than she normally would have.
10-14 You face a hard choice of how deeply to invest yourself in sabotaging your fellow PC. Choose 1:
- Reduce their result by one tier, but suffer a cost or complication for it.
- Your hindering remains inefficient and removes nothing from their result.
-9 This went wrong badly. Choose 1:
- Accidentally improve the other character’s result by one tier.
- Hurt yourself or get in trouble in the course of your interference. The GM makes a Move against you.
You can use any of the standard repertoire that seems to fit the particular situation and characters involved. You hurt yourself or someone else, draw unwelcome attention, lose something important, get yourself (or someone else) in a bad spot, destroy something valuable, use up resources, leave traces, etc.
Reasons for Using This
If you're unhappy with the Corebook move only offering some simple numeric modifiers, and would like more interesting things to happen when the spotlight shines on characters trying to assist (or sabotage) one another - use this.
It has a greater chance of affecting the outcome of the helped/hindered PC's roll than the Corebook version, so you get a bit more bang for your willingness to use up your spotlight "merely" in support of a fellow PC.
Reasons Not To Use This
If you want to keep things fast-flowing, and not detract attention from elsewhere in a tension-ladden scene - probably don't use this.
There is a clear caveat to this variant move: It can tend to derail things a bit, as the helping/hindering character is prompted to make choices, weigh consequences against each other, and so on. Additionally, as soon as costs and complications are to be chosen, the GM must take care to maintain a tight reign on the scene's direction and pacing - keep in mind that the most important thing to focus on should still be the acting (not the helping/hindering) PC's move, and that should resolve dominantly in the narration.
Whatever cost, hurt, unwelcome attention, bad spots, or loss of resources the other person has to deal with as a result of their interference, should probably be handled later - or alternatively very briefly - in order not to muddy the waters of your fiction too much.
This variant houserule is being playtested in a game I'm in right now, so there may be additional insights to share about it some time down the line. In the meanwhile, comments and opinions are welcome, especially (but not exclusively) if you should feel inclined to playtest it yourselves, definitely let me know your thoughts!