Understanding 前世で因縁でもあった

Question

1. なぜか彼女の体格ーーというか主に胸部ーーを見ていると、遥か昔に受けた耐えがたい屈辱を思い出すかのような感覚に囚われた。......前世で因縁でもあったのだろうか。 (Date a live, novel)

2. 前世で因縁のある相手に求婚されました。

https://www.alphapolis.co.jp/novel/386289103/512357378/episode/2752663

3. そして実は、この3人以外にも前世で因縁があった人が、現在の彼らの中にいることが判明していきます。

http://americanwhiskeynyc.com/p/4123026891530/?i=94133&fdA3Zg.donnish

Please have a look at these sample sentences. I have 3 questions.

1. In the first sentence, is the でも in 因縁でもあった used in the same way as in お茶でも飲みませんか。? So grammatically, this でも is almost equivalent to が? If not, how should I understand the でも?
2. Is 前世で rather than 前世に used in these sample sentences because 因縁があった(ある) is considered as an action? Since in the pattern 「AにBがある」, に indicates the place where B exists while で is for the place where an action takes place.
3. Is there any difference between 前世で因縁があった and 前世で因縁がある?

Answer 1

1. Yes. 因縁があった is "there was an 因縁", whereas 因縁でもあった is "there was an 因縁 or something like that". 因縁 is originally a Buddhism term, but it has been neutralized and can refer to any old human relationship that indirectly affects someone's fate.
2. ある is a plain existence verb here, but 前世 refers to a time range rather than a place, so you don't have to use に.
3. Of course ある puts more focus on the current situation, but the difference is small in your examples.

Answer 2

1. Yes, でも is used to give a example "Let's drink some tea?"「お茶でも飲みませんか。」. Whereas 「が」 is used to justify/explain something related to the object/person.

   • 僕　が　間違ってたから。 Because I was wrong.
   • 月　が　綺麗ですね。 The Moon is beautiful.
   • 明日に でも 伺います。Like tomorrow I will visit.

2. 「あった」 is used to express the possession, e.g., "had blabla". In this case, (had a karma) in the previous life.

3. 「あった」 is equal to had and ある is the same as have. So you should use the past form 「あった」 or add 「からの」(from the) so we have 「前世からの因縁がある」（Have a karma from the past life）.