Interrupt

Interrupts are an addition to the dialogue system in Mass Effect 2. They allow Commander Shepard to take direct, often physical, action at certain moments in conversations.

Mechanics
There are two types of Interrupts, each corresponding to a side of the morality scale, Paragon and Renegade.

During conversations the player may be presented with an Interrupt icon, either a blue icon in the bottom left corner (right on the PC) of the screen, for Paragon interrupts, or a red icon in the bottom right corner (left on the PC) of the screen, for Renegade Interrupts. Pressing the corresponding mouse button (PC), or trigger (Xbox 360, PS3), will activate the interrupt, allowing Shepard to take some form of direct action. A Renegade interrupt, for example, may have Shepard physically assault another character, while a Paragon interrupt might have Shepard intervene to prevent one character from harming another.

Interrupts are usually available for no more than a couple of seconds, and are entirely optional. However, as with Charm and Intimidate dialogue options, they may allow Shepard to avoid, or decrease the severity of, some conflicts.

Using a Renegade or Paragon interrupt will typically result in a significant number of the appropriate Renegade or Paragon points being awarded. Usually, Not using an interrupt is not considered a moral choice, I.E. not using a Paragon interrupt is not considered a Renegade choice, or vice versa. However there are a few exceptions to this rule in various points throughout the game.

Freedom's Progress
After finding Veetor, babbling in a paranoid manner about monsters out to get him and watching garbled footage on a wall of monitors, the player is presented with a Paragon or Renegade interrupt, depending on whether a Renegade or Paragon dialogue option is chosen.

Dossier: The Professor
Soon after entering the quarantine zone the squad will encounter a batarian plague victim. He will accuse humans of spreading the plague before entering a coughing fit.

After meeting Mordin for the first time Mordin will attempt to figure out who the squad is, rapidly thinking out loud.

After Mordin is brought aboard the Normandy and told about the situation with the Collectors he will try to figure out how they are able to take whole colonies without a trace, again doing so rapidly and out loud.

Dossier: Archangel
If Shepard is female, when going to sign up as a freelancer, the Blue Suns mercenary will try to redirect Shepard to the strippers' quarters.

After signing on as a freelancer to take on Archangel, a young man who wants to become a freelancer enters.

While talking with Sergeant Cathka, who is working on the gunship, Shepard will notice an electric tool on the bench.

After meeting up with Archangel, he will give Shepard his Sniper Rifle to survey the advancing Eclipse mercenaries.

Dossier: The Warlord
Shepard meets a wounded merc shortly after the start of the mission. While talking to the merc, he is radioed from Headquarters requesting to know his status. Shepard can use Charm or Intimidate to convince the merc to reply with false information, which allows the Commander to interrogate the merc further. Otherwise, Shepard can tell him to remain silent - in which case he'll try to inform the Blue Suns about Shepard anyway, leading to an interrupt.

If you use Intimidate instead of telling the merc to remain silent, you will earn +5 points to both Renegade and Paragon. This also allows you to question the merc further. Also note that triggering this interrupt will not forfeit the +2 Paragon/Renegade points you get for your initial dialogue line.

Dossier: The Assassin
After arriving at Dantius Towers the squad finds a salarian worker who is gravely wounded. During the conversation he struggles to breathe and asks for help.

After exiting an elevator the squad will encounter an Eclipse mercenary. Catching him of guard Shepard interrogates him, hoping to learn the location of the assassin. The merc is uncooperative and backs up against a window as Shepard moves in.

After bypassing their way into a small room the squad will find several salarian workers and a dead Eclipse mercenary. One of the salarians, terrified, will threaten the squad with a weapon and tell them to stay back.

Dossier: The Justicar
After talking with Samara at the crime scene, Shepard is instructed to question Pitne For regarding the location of the Eclipse boss. Shepard confronts him about previously lying to the Commander about his involvement in local criminal affairs.

Inside the Eclipse offices Shepard finds Elnora, an asari mercenary hiding behind a table. The mercenary begs Shepard to let her go, claiming that she is only a rookie who's joined the mercenaries by mistake and has not done even anything wrong. She then pulls a gun on Shepard.

Right outside Captain Wasea's office, Shepard runs into Niftu Cal, a volus high on biotics-enhancing drugs. He boasts about his new-found powers, and proceeds to claim that he will personally defeat Wasea.

Garrus: Eye for an Eye
The squad arrives at the warehouse and encounter a volus claiming to be Fade. When Garrus makes it clear that they want to make someone reappear, rather than dissappear, the volus refuses to cooperate. Garrus draws his weapon and the volus commands his two krogan bodyguards to open fire.

After dealing with "Fade", Shepard and Garrus travel back to the wards to meet with Sidonis. Garrus sets up to snipe Sidonis while Shepard distracts him in conversation. If Shepard tells Sidonis that Garrus is trying to kill him, Sidonis attempts to run away.

Grunt: Rite of Passage
After meeting with the Urdnot clan leader, the team can head upstairs to speak with the shaman, who is engaged with Gatatog Uvenk in a heated conversation regarding Grunt. The Shaman is not at all dissuaded by Grunt's origins, yet Uvenk will continue voicing his distaste on the matter.

Jack: Subject Zero
Shepard and the squad find Aresh, a former subject of the Teltin project, hiding in Jack's old cell. When Aresh explains that he wants to rebuild the facility and restart the project, Jack goes into a confused fury, hits Aresh with some biotics, and finally puts a gun to his head.

Jacob: The Gift of Greatness
After moving beyond the Gernsback the squad comes across a woman speaking incoherently about people from the sky that would save them. As she talks Shepard spots a group of armed men sneaking up behind her. One of them aims his weapon and prepares to fire.

Miranda: The Prodigal
After arriving at the cargo area, the squad is approached by an Eclipse mercenary who informs them that they're too late and his captain, Enyala, is moving in on Oriana and that Niket won't be helping Miranda. Miranda angrily accuses him of lying before the merc tells them that their conversation has given his snipers time to get in position.

After arriving at Dock 94 the squad finds that Niket has betrayed Miranda and is attempting to return her sister to her father. After a brief conversation Miranda moves to shoot Niket.

Mordin: Old Blood
About halfway after the squad has infiltrated Clan Weyrloc's hospital-turned-base, a Weyrlock Clanspeaker hails Shepard from atop a ledge overlooking your position. He begins ranting on about the coming glory of Clan Weyrlock, revealing that Mordin's old assistant Maelon is working on a cure for the Genophage. Shepard then spots a flammable tank just under the krogan's position.

Once the team finds Maelon at the end of the mission, he reveals that he is working voluntarily and that all the atrocities he has committed in his experiments were necessary. After a brief exchange, Maelon pulls his gun on the squad before Mordin blindsides him and brings his own pistol to bear, claiming he must end the experiments, and Maelon.

Tali: Treason
Shepard locates the body of Rael'Zorah, Tali's father, on the quarian ship Alarei. Tali runs up to the body and frantically tries to find masked signs of life or any indication that her father is not really dead.

Thane: Sins of the Father
Captain Bailey sends Shepard to talk to Mouse, a criminal contact in the upper Zakera Ward, to find information about the people who hired Thane's son. Mouse is not eager to reveal his clients, as he is afraid for his own life.

Overlord: Vulcan Station
After arriving at the override controls in Vulcan station, the squad shoots the arms off a LOKI mech, which begins to run around aimlessly. Shepard then contacts Dr. Archer to report success.

Overlord: Atlas Station
After preventing the VI from uploading itself to the Normandy, Shepard discovers David Archer hooked up to the core via a series of intrusive tubes and clamps, begging for mercy. Dr. Archer argues that the experiment must continue, and Shepard is given a choice: free David and deliver him to Jon Grissom Academy, or continue the experiments.

If the decision is made to deliver David to Grissom Academy, Dr. Archer draws a gun and shoots at Shepard. Shepard will dodge the attack and put a gun in Archer's face.

Interview with Khalisah Al-Jilani
At the far end of the Zakera Ward Level 28 on the Citadel, Shepard meets Khalisah al-Jilani, a news reporter whom the Commander met during Mass Effect. Khalisah wants to make a follow-up interview, and confronts Shepard about the Commander's decision to let the Destiny Ascension be destroyed, or sacrifice human soldiers to save the ship.

Striking Ms. al-Jilani does not nullify the +2 Paragon/Renegade points you get from your initial response when meeting her.