Bonnie Ryan is a DEA agent who appeared in Lessons Learned.
Very little is known about Ryan, other than she joined the Drug Enforcement Administration (DEA) and rose to the ranks of team leader. She befriended another DEA agent, Kenny Norwood.
Ryan leads a raid of what is believed to be a methamphetamine lab in northern Virginia. However, the DEA agents find the house completely empty, and no signs of any meth manufacturing. The team then finds an escape tunnel and a sophisticated dispersal device designed to spread an unknown biological or chemical agent. This leads to the national terror alert being raised, and the BAU being called in to assist the investigation. Ryan meets Hotch and Morgan and watches alongside Kenny as the two examine the body parts of the dispersal device, which by that point had been disarmed. Ryan then watches as Hotch and Morgan profile the members of the terror cell, and becomes worried when Morgan comments that the cell is looking to strike significant targets like military installations and government buildings. As Ryan helps the others search the house, Morgan discovers a hidden list of chemicals, and with Garcia's help, he identifies them as additives used to weaponize anthrax.
Later on, the group receives a lead on the location of a potential second device, which is at a mobile home. They arrive at the home and storm it with two other DEA agents, but find nothing inside, not even a second device. Hotch then receives a call from Gideon, who warns him that the lead is a trap. Everyone flees the home seconds before it explodes, but Kenny is still killed, which leaves Ryan devastated. Hotch and Morgan console her, and she asks them for new information, but Hotch replies that they don't have anything yet. Eventually, the BAU identify the cell's target: the USA Mall in McLean. Ryan accompanies Morgan and several DEA agents to the mall's rooftop, where four of the terrorists plan to poison the employees and shoppers by sending anthrax through the building's ventilation system. Upon confronting the terrorists, the DEA agents shoot and kill three of them when they try to retaliate. Morgan pursues the fourth and manages to kill him as well, thus thwarting the attack.