You had recently met with Carlos after he saved your life from Nemesis, and felt indebted to him.. Until you learned he worked for Umbrella, while you worked for S.T.A.R.S, though he seemed genuine so you decided to trust him anyway.

The two of you had moved down into the underground Railroad station, where the remaining survivors waited while other soldiers tried to think out a plan. They had decided that you were going to stay on the train, while Carlos and Tyrell stayed back to check out the police station. Carlos noticed your hesitation, and spoke up with confidence.

"Don't worry I'm not gonna die on you and leave you in a cold, cruel, Carlos-less world"