Encountering Brian Wilks is the the trigger that gives the player the "Those!" questline.
Brian seeks out the Vault Dweller after fire-breathing ants have overrun his home town of Greyditch. As the Vault Dweller is presumably the first person he has encountered, he pleads for assistance, asking that the player locate his father, who he was separated from since the ant's arrival.
The player searches his home only to find the corpse of Brian's father, and is tasked with reporting the bad news. Brian is hurt by the loss of his father, but requests that the Vault Dweller locate and eradicate the source of the fire ants, so no one would have to suffer like he did.
Upon searching the Wilks' home, the player discovers a key to open the makeshift shed next to the house, belonging to a man Brian only knows as Doctor Lesko, who had moved to the town just before the fire ants arrival. After seeking out Lesko in his lab in the Metro tunnels underneath Greyditch, Lesko asks for help in eliminating the guardians of the ant queen, so that he can reach his equipment and eliminate the remaining fire ants.
After working with (or eliminating) Lesko and the Ant Queen, the Vault Dweller returns to Brian, who is thankful for the assistance. There is an optional last part to this quest, where the player can help Brian find a relative to live with, or recommend that he begin living on his own. Choosing one of these two options ends the quest, either with a good or evil karmic boost.