They don't tend to go around suited up in public often but when they do ponies still somehow fail to realize who they are despite that very Rarity mane-style. Luckily their voice is QUITE different, as Agony causes them to speak in a lower rasp quite unlike Rarity's high and haughty manner. They're still very charming though. When they want to be.
When not suited up Agony tends to provide opinions to Rarity as she works on dresses and is more than happy to hold tools and pass things to her. Rarity enjoys having someone to bounce ideas off of. They learn to get along better than most of the other symbiotes do with their pony hosts, surpassed only by Twilight and Venom's quick fondness of each other. Though Pinkie and Hysteria wasted no time becoming best friends either.