Yoshitaka Amano artwork and Interceptor's game sprite suggest he is most likely a Doberman Pinscher, Beauceron, or a mix of the two. He may also be related to the Vector Hound enemies. Doberman Pinschers are well known as intelligent, alert, and tenaciously loyal companions and guard dogs.
Shadow likes to claim that Interceptor eats strangers, although whether or not this is true is never stated. Interceptor also apparently eats expensive food, as Shadow asks the player for 3000 gil to feed him at one point in the game. Interceptor can be ruthless at times, especially when Shadow is in danger, but he is friendly and playful to Relm Arrowny.
Shadow acquired Interceptor from the town of Thamasa, during the time he settled there and was living a peaceful life with a local woman. At some point, when Shadow decided to change his name and leave town, Interceptor decided to follow him, even though Shadow told the dog to stay. Since then, the two have become inseparable.
The party first encounters Interceptor in South Figaro along with Shadow inside the pub. Shadow warns the party to stay away from them. After the events of the Lete River, Sabin ends up separated from the rest of the party. He meets up with Shadow and Interceptor outside Gau's father's house, whom then both join Sabin. Interceptor and his master travel with Sabin for a short while, until they both end up leaving Sabin and Cyan when the group arrives at Baren Falls. The party later encounters Shadow and Interceptor again in Kohlingen's inn. Shadow asks the party for 3,000 gil to feed his dog in exchange for their services. If accepted, Shadow and Interceptor will leave the party after the events in Zozo.
Much later in the game, both Shadow and Interceptor are recruited by General Leo on a mission of goodwill to the Espers. On their arrival on Crescent Island; Shadow and Interceptor, along with Locke and Terra, go searching for the Espers and end up in Thamasa. While searching the town, they begin talking to Strago about the Espers when his granddaughter Relm suddenly interrupts their conversation to meet the strangers. She begins to ask about them when she notices Interceptor and begins to play with him. Despite a warning from Shadow about the dog's demeanor, Interceptor follows Relm up to the second floor of the house, leaving Strago to apologize for Relm's actions; Shadow dismisses the apology, only noting that Interceptor doesn't usually like other people. After the conversation, Shadow calls for Interceptor and they leave the premises together, ultimately ending up staying the night at the local inn with the party. During the night, Strago rushes into the inn and asks for Locke and Terra's help in rescuing Relm who is trapped inside the Burning Home; they agree and leave the still sleeping Shadow behind. When Interceptor also takes his leave, Shadow wakes up and calls for the dog, only to discover that he is nowhere to be found.
Terra, Locke, and Strago end up defeating the source of the blaze deep within the house, only to find Interceptor trying to protect the unconscious Relm. When the house begins to collapse, the party is knocked unconscious as well, and Interceptor is the only one left unharmed. He begins barking at the flame monsters in an effort to protect the unconscious party, when Shadow suddenly arrives; defeating the enemies and using a smoke bomb to escape with the group. Once the party has recovered, Strago agrees to join Terra and Locke in their search for the Espers out of gratitude. When Strago thanks Shadow for his help in saving Relm, he replies that he did so only to get his dog back, before the pair leaves Thamasa on their own to search for the Espers in their own way.
After the Battle of Thamasa, a wounded Interceptor approaches the party near General Leo's grave, causing Locke to conclude that Shadow was killed as well. Locke tends to Interceptor's wounds a bit and Relm tells him that she'll take care of him. Interceptor and Shadow become separated from each other when the Floating Continent rises into the sky, and Interceptor remains behind in Thamasa waiting around the area of General Leo's grave.
Depending on the player's choice regarding waiting for Shadow on the Floating Continent, Interceptor's story will differ slightly. In the World of Ruin, when the party reaches the Cave on the Veldt, Interceptor will bark at the party, and run deeper into the cave. The party comments that Interceptor wants them to follow him further inside. Upon reaching the deepest area of the cave, they find Interceptor standing next to a wounded Shadow or Relm lying on the floor; the party is then attacked by a monster when they check on their fallen party member. Upon the monster's defeat, the party will fly the wounded party member back to Thamasa to recover. Once there, Shadow/Relm will rest in Strago's house while Interceptor will keep watch on him/her.
If the player waited for Shadow on the Floating Continent, both he and Interceptor will join the party after Shadow is defeated in the Dragon's Neck Coliseum. If the player did not wait for Shadow, Interceptor will join the party with Relm after the events at Owzer's Mansion.
After the party has defeated Kefka and is escaping his crumbling tower, Shadow orders Interceptor to leave him behind, to which he complies and escapes the tower along with the rest of the party.
Interceptor can help out in battle if Shadow is in the party, although not on the Floating Continent since Interceptor is in Thamasa. Since Interceptor's in-battle assistance is implemented as a "not named in-game" status effect, the Rippler bug makes it possible to lose Interceptor permanently. If Shadow is attacked physically, there is a chance Interceptor will take the hit for Shadow, and thus how much damage Shadow could have taken will be displayed.
If this happens, there is a small chance Interceptor will counterattack with Takedown (spell power of 55) or Wild Fang (spell power of 66). There is a 50% chance of each being picked. Both abilities deal defense-penetrating magic damage to one enemy. These counterattacks will miss on floating targets. If Gogo uses Mimic right after Interceptor's attack, he can call Interceptor to perform the attack again.
If the party abandons Shadow on the Floating Continent, the "not named in-game" status effect will be applied to Relm.
Interceptor makes a cameo appearance alongside Shadow and acts as tutors for the in-game manuals.
Interceptor appears in Shadow's official artwork, but did not appear in the game until the introduction of Relm.
Interceptor appears in some of Shadow's cards in Final Fantasy Airborne Brigade using his attacks from Final Fantasy VI.
Interceptor appears as part of Shadow's Soul Breaks.
Interceptor appears in one card for the game, represented by his Amano art with Shadow. As in Final Fantasy VI, Interceptor protects Shadow, reducing all damage to the player's Shadow cards to 2,000, and he is able to use his Wild Fang ability to increase his power temporarily.
Interceptor's name is befitting to his role in the game, intercepting attacks for Shadow.An interceptor is a person or thing that stops or catches (someone or something) going from one place to another.