You Scratch My Back, I'll Scratch Yours

You Scratch My Back, I'll Scratch Yours is a mission in Deus Ex: Human Revolution. It is available within the Explosive Mission Pack or The Director's Cut and is interjected between the completion of the Find Vasili Sevchenko's GPL Device objective and the start of the Stowing Away objective, during Jensen's second visit to Hengsha.

Meet the Harvester contact

 * Meet one of Tong's Harvester thugs in the sewers below the Alice Garden pods.

Rescue Tong's son

 * Infiltrate the abandoned noodle factory and rescue Tong Jr. from Belltower Associates.
 * Give him the Harvester contraption.

Meet Tong in the Harvester hideout

 * Complete the mission and receive Grenade launcher.

Trivia

 * There exists an air shaft allowing the player to observe Tong Jr. from above, before freeing him. After listening to him conversing with himself concerning his present predicament, he will whistle a tune. This tune happens to be the main theme for the first Deus Ex in which Tracer Tong plays a primary role.
 * If you repeatedly leave and re-enter the air shaft, Tong Jr. may do a couple of different things. Besides often botching the last note when whistling the first Deus Ex theme, he'll also complain that the guards keep giving him Lemon-Lime soda instead of Orange (a popular reference to Deus Ex). Related to this, an e-mail can be found in this mission which addresses Tong Jr.'s demands upon his guards for soda.
 * This part of the mission is very clearly a reference to Metal Gear Solid, where the protagonist, Solid Snake, climbs through ventilation to discover an imprisoned soldier named Meryl. If Snake leaves and re-enters the vent, Meryl will be performing a different action than before. Leaving and re-entering the vent, to change what Meryl is doing, can be repeated over and over.
 * Additionally, the Unknown Handheld Device that Tong Jr. uses to escape is very much like the Stealth Camouflage that another character, Otacon, uses to evade enemy detection throughout the game. In both Deus Ex: Human Revolution and Metal Gear Solid, this device was most likely used to explain why there is no need to protect or escort each game's relative character to safety, as both characters are heavily implied to be incapable of efficiently defending themselves.
 * Upon rescuing Tong Jr., Adam will have a somewhat lengthy conversation with Tong Jr. concerning his youthful and foolhardy ways. Adam seems to successfully make his point once he points out, "The more power you think you have, the more quickly it slips through your grasp." This seems to have made an impression as it is one of Tracer Tong's more well known quotes from Deus Ex.
 * Above the last room with guards there are two destroyed levels, seen through a hole in the ceiling. Although they seem to be unreachable even with augmented jump and crate stacking, one may see there a large crate with Sarif Industries logo as well as a plush toy overseeing the location.