every single person is capable of making a real difference in their own small way, for example I have convinced multiple people new to the series to start with Dark Souls 2
I bounced off the first Dark Souls pretty hard, but I fell in love with DS2. the fact that enemies stop respawning if you kill them enough makes even defeat feel progressive while you're learning, and many bosses specifically reward exploration (e.g. turning the lights on the Lost Sinner's arena).
you cannot pet the cat but you can (and should) talk to her all the time, she has a ton of dialogue and will say something new at every story advancement. also she moves around the room she's in, and sometimes scratches the wall.
I remember I joined Alvinia's covenant in DS1 and went right back to farming her minions for souls, whoops. She Did Not Like That
you can get the Silvercat Ring in DS3 but there's no actual talking cat, one of many reasons why it's the inferior Dark Souls. I haven't played all the DLC yet though