How does applying drained to an Eidolon affect the Summoners hitpoints?

Question

While in the course of play, one of the enemies gave the party summoner's eidolon drained 1. We were unsure whether to change the summoner's hit points, since they are shared amongst the two. Normally an eidolon and their summoner "share a single pool of Hit Points", and "Damage taken by either you or the eidolon reduces your Hit Points". However... drained specifies that "Losing [the Hit Points from drained] doesn’t count as taking damage", and lowering the max health also seems to be technically not damage. What should we be doing in this scenario? These are the options I see:

1. Don't modify the hit point pool, but reduce the Eidolon's Fortitude Save and other Constitution based abilities by the appropriate amount.
2. Apply the hit point loss of drained to the health pool, but not the max hit point reduction. Only the Eidolon takes the penalty to things associated with Constitution.
3. Apply both the hit point loss of drained and the max hit point reduction to the health pool. Only the Eidolon takes the penalty to things associated with Constitution.

In session, I ruled 3, since making Eidolons immune to the strongest part of the drained condition seems overpowered. However, the player's Hero Lab sheet went with option 1. Obviously Hero Lab is not an authoritative source; but did I make the right ruling?

Answer 1

#3 is correct

The line immediately after the portions you include in your Question sums it up fairly well:

Like with your actions, if you and your eidolon are both subject to the same effect that affects your Hit Points, you apply those effects only once (applying the greater effect, if applicable).

The shared pool is not limited to damage but is affected by any Effect (read: anything) that "affects" Hit Points. Drained is a Condition with an Effect that your current and max Hit Points are reduced. This reduction would still be limited to whichever member of the duo has the greater Drained value; them both having Drained 1 would result in the same Hit Point maximum as either of them having it.