The Duel of Faro was an open confrontation between Vin-Tak and Sif, who had been sent to Earth so she could learn what the Kree warrior was planning.
Background[]
During a war between the Kree and another race, the Kree suffered high casualties and became divided on how to even the odds. One particular group of Kree dispatched science teams across different worlds, experimenting on various alien races in order to produce bio-weapons. One of the planets visited was pre-historical Earth; the humans were the most successful species to be subjected to the Kree's experiments, which gave rise to a sub-order called the Inhumans. The Inhumans had the potential to obtain supernatural powers and characteristics if exposed to the Terrigen Mist, a mutagen exhaled from Terrigen Crystals. The Kree created Diviners to carry the crystals, and they were built to only recognize the unique genetic patterns in Inhumans.
A Kree named Vin-Tak came to Earth when he noticed that a Diviner had been activated; believing the Inhumans as abominations, and fearing what would happen if the Kree Empire found out about them, he sought to kill whoever had transformed.
The Asgardians and the Kree developed a racial dislike for one another; when Heimdall saw a Kree arrive on Earth, one of the planets under his watch, he alerted his king of the occurrence. Sif was sent to investigate.[2]
Duel[]
Lady Sif tracked the Kree Vin-Tak to the city of Faro in Portugal, and they engaged in a fight in one of its piers. Vin-Tak managed to hold his own against Sif, blocking her sword with his Truncheon while they exchanged some blows.
Sif managed to hit Vin-Tak in the chest, damaging the device that he used to pose as a human and turn his skin from blue to pink, and making it lose the liquid nitrogen that used as fuel. The liquid nitrogen hit a nearby lamppost, freezing it solid.
Vin-Tak used this as a distraction, hitting Sif with his Truncheon and making her lose her memories. With Sif now at his mercy, Vin-Tak threw Sif to the sea.[2]
Aftermath[]
May, Coulson and Sif investigate what happened during the duel
- "Look, just tell us what you saw after they fought."
"The man destroyed my booth!"
"What does he want with balloons?"
"He went for my helium, broke off the valves, and took them!" - ―Phil Coulson, Cardozo and Melinda May[src]
Vin-Tak attacked a balloon stand at the pier owned by a man named Cardozo, in order to steal the valves from the helium tanks and repair his nitrogen device.
Sif emerged from the sea and was eventually detained by Portuguese authorities. A S.H.I.E.L.D. agent among them contacted Director Phil Coulson and alerted him to the presence of the Asgardian ally. Coulson took Melinda May with him to collect Sif while Lance Hunter, Alphonso Mackenzie and Leo Fitz surveyed the beach where the duel occurred for clues for her combatant and how she lost her memory.
Sif was interviewed by Coulson and May, while Hunter, Mackenzie and Fitz examined the "crime scene". Accessing to videos posted on social media, S.H.I.E.L.D. got the first glimpse of the individual who used a Truncheon to defeat Sif.[2]