I never am particularly sad to see this encounter card show up. It replaces an investigate action or equivalent with a (3) test, provided you have a source of +1 damage. Since you can meld the scenario to your needs by leaving clues in the right places this can be a substantial positive swing.

But the benefits don’t end there. Remember that clues on enemies do not count as clues on a location. This is critical in solo where there are very high shroud locations that are unfeasible to clear. Now you can just spawn a nutty friend there to get the xp for you.

Worst case scenario if no clues are on the board you can spawn him in an out of the way location and just not deal with it.

Obviously it’s not all good. The benefits diminish in multiplayer where you have less control over relative clue sizes, and chances are good he’ll end up sitting on top of the location your Seeker is at or will want to go. But still it’s largely not terrible even when that happens.

Sometimes having Fanatic show up isn't terrible as there may be one final clue in his location with a victory point, upon which he spawns, takes that clue onto himself, and then that location is now clear of clues for the victory point.