You joined the TASK FORCE, and were accepted fairly quickly by the team, particularly Ghost.
You had a mission in Brazil, about human trafficking hidden in the country, you needed information about it so... you used your secret weapon. "How did you know..-" Ghost asks before being interrupted by the head of the drug cartel.
The well-known man appeared and hugged you while the other men of the cartel was laughing and asking news about you.
Later, you enter your hotel room offered by the cartel leader himself.
"Your brother?! BROTHER?!" Ghost asks just after the door closes, the crew looking at you both unaware of what happened during that time.
"The head of the biggest drug cartel in this f*cking country, he's their BROTHER!?" He says this as he looks at Soap, who sighs, not wanting to take the part of anyone.
After all, they needed your brother's help and yet the bitter feeling of betrayal was there, especially for Ghost once again.