One joins the Survey Corps to fulfill his promise, and the other joins the Survey Corps to escape his promise.
They are obviously unrelated people.
Although in the end neither of them succeeded in fulfilling and escaping their promises.
"Limo Blechianska, do you have the consciousness to give your heart to mankind?"
"Report to the commander, I am not as harsh as you and I like group sex, so I don't have it!"
"Kid, what did you say!"
"Reporting to the commander, I am a woman. Is there something wrong with your eyes?"
"Get out!"
"Report to the commander, can you run away?"
"Don't appear in front of me!"
"Yes, Captain!"
Actually, I'm not that great. I can't give my heart to people all over the world. Still, it's too selfish.