Blind Familiar trying to deliver a touch spell

Question

Here's the setup:

• My familiar is adjacent to a target. My familiar is blinded.

• I cast a touch spell. My familiar uses its reaction to deliver the spell (which requires an melee spell attack roll).

Normally, being blinded causes you to attack at disadvantage, so I attack at disadvantage, right? I'm nearly certain about this, but wanted to confirm.

Background reading:

If I'm blinded, can I cast a spell that doesn't require that the target be "a creature you can see"? (mentions casting while blind, but not specifically the issue of a familiar delivering a touch spell)

Blinded + casting a spell with a bonus action + Find Familiar

Does an invisible familiar delivering a touch spell have advantage?

Answer 1

Yes your blinded familiar has disadvantage on the attack roll. If the familiar gets advantage from another source like invisibility there is neither advantage nor disadvantage.

P173 of the Player's Handbook:

Advantage and disadvantage

If multiple situations affect a roll and each one grants advantage or imposes disadvantage on it, you don't roll more than one additional d20. If two favorable situations grant advantage, for example, you still roll only one additional d20. If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage.

Answer 2

The text of Find Familiar uses the wording "as if [the familiar] had cast the spell". If the familiar cast a spell which required an attack roll, its blinded condition would impose disadvantage on the roll. The same is the case when delivering a spell you cast.