Rank 10 Chocobo Reached!

[Nedhitis]

Is killing random mobs the ONLY way to earn companion experience...? No shared quest experience or anything...? Because that seems very tiresome.

[Maelwys]

Is killing random mobs the ONLY way to earn companion experience...? No shared quest experience or anything...? Because that seems very tiresome.

Currently they consume a set percentage of the EXP from each mob you kill (so you will get slightly less exp for your own character) but they don't get any of the bonus from Quest completions, FATEs, LEVEs etc.

They do get bonuses from EXP chains, so repeatedly chaining high-level enemies is currently the quickest way to level them up (you can hit Chain4/Chain5 solo easilly but will likely need a team or carefully timed pulls and AoEs for anything higher). But yes, it still takes ages and is quite tiresome, especially if you're not used to old-style exp chain grinding like in the early days of FFXI.

I've not tested whether they get bonuses from your Rested EXP or food.

There is also a Free Company action buff named "A Man's Best Friend" that can increase the EXP earned by companions by 5%.