Out of curiosity, is it possible to have two familiars?
As far as I know there are two possible ways to obtain familiars. One is with the find familiar spell; the other is to find a creature with the familiar variant option.
In the first instance, the rules specify that you can't have more than one familiar, but the way is worded seems to be referring to the find familiar spell:
You gain the service of a familiar, a spirit that takes an animal
form you choose.The familiar has the statistics of the chosen form, though it is a
celestial, fey, or fiend (your choice) instead of a beast.You can’t have more than one familiar at a time. If you cast this
spell while you already have a familiar, you instead cause it to adopt
a new form.
But in the variant case you don't have a spirit per-se; you have the actual living thing and it does not change forms (as in the spell). Also, there is nothing in the variant rules that seems to rule out the option of having two familiars:
Variant: Quasit Familiar
[…]
The quasit can serve another creature as a familiar, forming a telepathic bond with its willing master. While the two are bonded, the master can sense what the quasit senses as long as they are within 1 mile of each other. While the quasit is within 10 feet of its master, the master shares the quasit's Magic Resistance trait. At any time and for any reason, the quasit can end its service as a familiar, ending the telepathic bond.
And, as far as I know, there is no limit on how many telepathic bonds you may have, if the telepathic communication and "possession" is considered a telepathic bond.
Therefore, is it really possible to have two familiars, particularly using both rules, the find familiar and the variant option, or I missing something?
Best Answer
There's nothing in the rules that prevents you from having the service of two creatures with the Familiar variant.
What you have to remember is that variant monsters, like monsters, are designed for the GM to use to make enemies more interesting. The Familiar variant is a monster variant, just like the troll's Loathsome Limbs variant or the Genie Powers variant. They're for GM use rather than player use.
The Mage NPC in Appendix B of the Monster Manual also has a Familiar variant, which says:
So the Familiar variant is for GMs to create more interesting NPCs, rather than to provide players with additional options. Of course, with your GM's permission, you could obtain one of these familiars. This would probably involve actually finding such a creature and somehow forming a bond with it. But this relies solely on your GM to allow and arbitrate.
Needless to say, if even getting one familiar this way is entirely up to your GM, getting two is, even more so. There's nothing in the rules to prevent it, but you'll have to talk your GM into it if you want to have a quasit on each shoulder.
Now for combining Find Familiar with the Familiar variant: The interpretation that causes the least difficulty is that the variant Familiar isn't actually a familiar, it just "serves you as a familiar". In this case, there's no interaction between Find Familiar and the Familiar variant, and everything is fine.
However, if the variant Familiar is a familiar, well...things get weird. If you have your familiar from casting Find Familiar, and you then bond with one from the Familiar variant, there's no way to tell what happens. You "can't have more than one familiar at a time", so you've already put the game in a paradoxical state. Your original familiar might vanish, or your new one might die, or, well, anything, really.
If you have a familiar from the Familiar variant, and you cast Find Familiar, then by the rules (when using the interpretation that variant familiars still count as familiars), you get to change the form of your variant Familiar. You probably don't want to do this, since all the forms you could change it to are weaker than the one you've got, but there it is.
The fact that these rules break down completely when faced with each other is just more evidence - the Monster Manual is not meant as a player resource. Sorry, but it's not. Every spell or ability (like Wild Shape) that would require a player to look at the Monster Manual says "your DM has the stats" or something similar. The Familiar variant was never meant for players to see. It belongs to the GM.