Question: What kind of group does Trym Torson and Emperor have in common?

full_context: Document 1: Darkthrone: Darkthrone is a Norwegian heavy metal band. It formed in 1986 as a death metal band under the name Black Death. In 1991, the band embraced a black metal style influenced by Bathory and Celtic Frost and became one of the leading bands in the Norwegian black metal scene. Their first three black metal albums—"A Blaze in the Northern Sky", "Under a Funeral Moon" and "Transilvanian Hunger" (sometimes dubbed the "Unholy Trinity") — are considered the peak of the band's career and to be among the most influential albums in the genre. For most of this time, Darkthrone has been a duo of Nocturno Culto and Fenriz, who have sought to remain outside the music mainstream. Since 2006, their work has strayed from the traditional black metal style and incorporated more elements of traditional heavy metal, speed metal and punk rock, being likened to Motörhead.
Document 2: Ivar Bjørnson: Ivar Bjørnson (born November 27, 1977 in Etne) is a Norwegian composer/guitarist for the progressive black/viking metal band Enslaved. He is, along with Grutle Kjellson, one of only two founding members left in the current line-up, being only 13 years old at the time of the band's formation in 1991. Bjørnson and Grutle Kjellson performed in a death metal band called Phobia in 1989. The two decided that they wanted to form a new band in a more black metal style, and after discovering their shared fascination with Norse mythology, this set the groundwork for Enslaved. Beyond his duties on guitar, he writes almost all of the music for Enslaved as well as much of the lyrics. He has said that "When we started Enslaved we wanted to have the same level of commitment to something spiritual as our contemporaries in black metal [have with] the Satanic side. The dark destructive part of black metal didn't seem right because we didn't have any commitment to any Satanic ideology." He contributed keyboard/synth work to Borknagar's first three albums and synth/piano work on the Gorgoroth albums "Incipit Satan" and "Destroyer" under the name "Daimonion"; and also produced the first demo from black metal band Orcustus.
Document 3: Mustis: Mustis is the pseudonym of Øyvind Johan Mustaparta (born 10 September 1979), a Norwegian keyboardist best known for his work in the symphonic black metal band Dimmu Borgir, as well as the black/thrash metal band Susperia. Mustis joined Dimmu Borgir in 1998 and has contributed to the further progression of their ambient, atmospherical, symphonic sound. This can be heard in songs such as "Progenies of the Great Apocalypse," which he composed, on their 2003 album, "Death Cult Armageddon". His other studio work with Dimmu Borgir includes "Spiritual Black Dimensions" (1999), "Puritanical Euphoric Misanthropia" (2001), and the re-release of "Stormblåst" (2005) and "In Sorte Diaboli" (2007). Mustis departed the band in 2009 and issued a statement in which he implied that he was being kept out of the proper registration for music he was writing. Due to this, according to his statement, he was fired by text message and he will be allowing "the resolution come from the lawyers instead of dealing with more dishonesty and lies on a one-on-one personal level."
Document 4: Satyricon (band): Satyricon is a Norwegian black metal band, formed in 1991 in Oslo. Satyr and Frost have been the band's core members since 1993. The band's first three albums typify the Norwegian black metal style. Since its fourth album in 1999, the band has strayed from this style and included elements of traditional heavy metal in their sound. Satyricon was the first Norwegian black metal band to join a multi-national record label (EMI).
Document 5: Ihsahn: Ihsahn (born 10 October 1975 as Vegard Sverre Tveitan) is a Norwegian composer, multi-instrumentalist, and vocalist. He is best known for his work with Norwegian black metal band Emperor. He has appeared in Thou Shalt Suffer, played in Peccatum with his wife Ihriel (real name Heidi S. Tveitan), and now devotes himself to his solo albums.
Document 6: Emperor (band): Emperor is a Norwegian black metal band formed in 1991, regarded as highly influential by critics and emerging black metal bands. The group split up in 2001, but reunited from 2005 to 2007 for a few festival dates and brief US tours, and again reunited in 2013 to 2014. The group was founded by Ihsahn (guitar/vocal) and Samoth (then, drums).
Document 7: Zyklon: Zyklon was a Norwegian blackened death metal band formed in 1998 by Samoth and Trym of Emperor, along with members of Myrkskog. Their style has been described as modern death metal with black and industrial undertones. After more than a 2-year hiatus, the band officially split up in January 2010.
Document 8: Gorgoroth: Gorgoroth is a Norwegian black metal band based in Bergen. It was formed in 1992 by guitarist Infernus, who is also the only original member remaining, and the band have since released nine studio albums. Gorgoroth are a Satanic band and have drawn controversy due to some of their concerts, which have featured impaled sheep heads and mock crucifixions. The band is named after the dead plateau of darkness in the land of Mordor from J. R. R. Tolkien's fantasy novel "The Lord of the Rings".
Document 9: Enslaved (band): Enslaved is a Norwegian extreme metal band formed by Ivar Bjørnson and Grutle Kjellson in Haugesund in June 1991. They are currently based in Bergen, Norway. Though the band's lineup has changed many times over the years, Bjørnson and Kjellson have been the sole constant members, and the lineup remained the same from 2004 to 2016. Following their 25th anniversary world tour, keyboardist/guitarist/vocalist Herbrand Larsen departed from the band after 12 years and six albums. He has since been replaced by Håkon Vinje.
Document 10: Tomas Haake: Tomas Haake (born 13 July 1971) is a Swedish drummer and main songwriter of the extreme metal band Meshuggah. He is known for his polyrhythms and technical ability. In 2012, Haake was named the 5th best Modern Metal drummer by MetalSucks.net. In the July 2008 edition of "Modern Drummer" magazine, Haake was named the number one drummer in the "Metal" category, as decided upon in the magazine's Readers' Poll.
Document 11: Immortal (band): Immortal is a black metal band from Bergen, Norway, founded in 1991 by frontman and bassist Abbath Doom Occulta (Olve Eikemo) and guitarist Demonaz Doom Occulta (Harald Nævdal). The pair worked with various drummers (including Grim, Armagedda and Hellhammer), and were later joined by current drummer Horgh (Reidar Horghagen) in 1996.
Document 12: Euronymous: Øystein Aarseth (] ; 22 March 1968 – 10 August 1993), who went by the pseudonym Euronymous, was a Norwegian guitarist. Euronymous was a founder of and central figure in the early Norwegian black metal scene. He was a co-founder of the Norwegian black metal band Mayhem. He was also founder and owner of the extreme metal record label Deathlike Silence Productions and record shop Helvete.
Document 13: Trym Torson: Trym Torson (born Kai Johnny Mosaker), or just Trym, is a Norwegian drummer, formerly with Zyklon. Torson started playing in the Viking metal band Enslaved and was later invited to play in black metal band Emperor. He co-founded Zyklon together with Emperor member Samoth. His style is heavily influenced by jazz, and he is known for his fast playing, often consisting of blast beats and double-bass drumming. He is also a tattoo artist.
Document 14: Mayhem (band): Mayhem is a Norwegian black metal band formed in 1984 in Oslo. They were one of the founders of the Norwegian black metal scene and their music has strongly influenced the black metal genre. Mayhem's early career was highly controversial, primarily due to their notorious live performances, the 1991 suicide of vocalist Per Yngve Ohlin ("Dead") and the 1993 murder of guitarist Øystein Aarseth ("Euronymous") by former member Varg Vikernes ("Count Grishnackh"), of Burzum.
Document 15: Tormentor (musician): Tormentor (* 05.06.1972) is a black metal musician who is best known for his work as guitarist with the Norwegian black metal band Gorgoroth.
ground_truth: band