The party Die Linke has a complicated history. Its biggest success came on the tail end of the merger with the WASG, which was a left-wing party that split off the SPD following many members' disappointment with the SPD/Green coalition government under Schroeder. A lot of its strongholds are owed more to the candidates themselves than the party, which has provided a certain stability while also giving those candidates a disproportionate level of influence in an otherwise supposedly democratic platform (more democratic than other parties, at least).
The party Die Linke also does not explicitly tie itself to a single leftist ideology. You'll find anarchists, Marxists-Leninists and Trotskyists, both radical social progressives campaigning for ongoing civil rights issues and social conservatives worrying about alienating reactionaries. This creates a lot of potential for "democratic discourse" or "in-fighting" (depending on which bias you prefer). It has also allowed the party to receive "protest votes", although those are now more associated with the far-right (and regionally right-wing extremist) AfD.
The party Die Linke also does not explicitly tie itself to a single leftist ideology. You'll find anarchists, Marxists-Leninists and Trotskyists, both radical social progressives campaigning for ongoing civil rights issues and social conservatives worrying about alienating reactionaries. This creates a lot of potential for "democratic discourse" or "in-fighting" (depending on which bias you prefer). It has also allowed the party to receive "protest votes", although those are now more associated with the far-right (and regionally right-wing extremist) AfD.