everyone. I am currently writing a paper on sentence final suffixes in Japanese especially those used in conversation. I encounter a problem as to what is the origin of -っけ (eg. 名前は何だっけ？) . Is it connected to the verb 来る？
Any monolingual dictionary would instantly answer your question. See here for example:
https://kotobank.jp/word/%E3%81%91-487968#E5.A4.A7.E8.BE.9E.E6.9E.97.20.E7.AC.AC.E4.B8.89.E7.89.88
The sentence-ending particle 「け」 as in 「～～だっけ/～～たっけ」 comes from the Classical auxiliary verb 「けり」, which is basically used for expressing a feeling of reminiscence and/or exclamation regarding a past event.
It has absolutely nothing to do with 「来{く}る」.
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3FWIW, classical けり may indeed be related to 来る. Per Shogakukan's 国語大辞典: 【回想の助動詞「き」と「有り」、または「来（き）」と「有り」の結合したもの】 Notably, reflective き has no 連用形, and the き form is the 終止形, so presumably it could never compound with another verb like this -- leaving the き from the 連用形 for 来る as the only grammatically plausible derivation. – Eiríkr Útlendi Jan 6 '18 at 7:29
