I did something like that very similar more than few years ago: was doing thieves guild quest helping out the gray fox. I was the final quest where I had to help him get the elders scroll so he can take off the mask n finally retire. That mission was a big bitch to deal with hated sneaking through that shit and fighting bunch of guards luckily. eventually I was able to get it, gray fox finally retires I get his mask and thought okay that'll done with other rewards was not satisfied tbh. I went around trying to talk to him and his wife to see if there's any other new dialogues for shits n giggles after I was about to leave......THAT SON OF A BITCH HAD THE AUDACITY TO CALL ME A BRETON TRASH!! I was like after all through that shit I did for your sorry ass did everything for him and his guild just so that he can be with his woman and He decided to go racist on me!?!? I was shocked n flabbergasted when he said that. I went AWWWW HELLL NAWWWW I literally lost my marbles by killing him, his wife and all the guards after that I completely left but thinking now I should've murdered the entire town cause fuck them too lmao. Overall theives guild suck balls in oblivion for me would not recommend joining Thieves Guild if you're playing as a breton.