Go to the spirit interview and give them the fake personality that they want to see. Be extroverted (because the pilots/HR women do spy on you all through the interview), socialize, and fake it all. Act like the biggest social butterfly with a smile on your face. Just don't mention anything about going to United, even though it is 100% true. Then get the job. Finish IOE. Then apply to United. Enjoy life. Spirit is nothing but a bridge to the legacies.