I know that people have posted it before, but today was the first time that they messed me up. I was in the outskirts in the subway going to get the safe combo and as I run into the store Ellie runs in after me and Tess just starts fighting the runner out of no where and all the infected just game and raped us.
Haha yeah i've seen tess do some crazy **bleep**. As devs have said it's quite hard to code multiple AI in stealth situations. I have found that when its just Joel and Ellie her AI is quite good so kudos to ND in that regard.
I've never had Tess, or any other NPC, start a fight without my initial move thankfully, but I have had most of them behave as if under attack by a swarm of bees. Regardless of the enemy's location(s), they will run around, jumping over stuff and even running into the mobs, unconcerned with breaking the tension lol. I mean non-stop too.
I also want to say that I never really had a problem with Ellie. I can recall a few occassions in which she ran to visual safety (not that it matters) and bumped a mob on the way, but usually her movements were smoove and sensible. A handful of times she would throw a brick before I was ready to pounce, but it always ended up being a good move. I got to swoop in and get the kill and **bleep** before any other mobs showed up.
Obviously it is super complex to code so many AI's in a situation that depends entirely on your own human ingenuity. I think ND did the best they could with current console tech.
It can look goofy at times though haha.
Last playthrough I was hiding a the base of some stairs in Pittsburgh, really only room for one, waiting for a hunter to walk down so I could choke him out. Ellie was scooting around on the landing looking for a hiding place I'd assume, she ended up going up the stairs a ways and stabbing the hunter. The AI is... erratic..
More than often I'm impressed by their helpfulness though. When I'm sneaking sometimes and stealthily taking guys out, if they see a good opportunity, and I have already engaged the enemy, they will do a stealthy-ish takedown of their own, which is always cool. I like Bill's stealth takedowns with the machete.