Mr. Wemmick is Jaggers’s clerk (a.k.a. sidekick) who lives in a self-built castle. He has two very different personalities, depending on where he is. When he is in London, he is all business and a bit gruff. When he is at home in Walworth, he is warm, welcoming, and generous of spirit.
Pip likes to hang out with him at the castle, because that’s where Wemmick gives the best advice. Inside of the castle, Pip finds a number of Wemmick’s inventions (like little flags that function kind of like modern-day caller ID). While he does not deviate from the rules in London, Wemmick is constantly tinkering and being creative at the castle.
Wemmick likes to keep his work very separate from his home, and when Pip tells Jaggers that Wemmick lives in a castle with an Aged Parent, Jaggers is utterly dumbfounded. Immediately following this revelation, Wemmick and Jaggers are very awkward around one another, and it is only when they are able to collectively yell at a client that the equilibrium of their relationship is restored.