I saw this sentence in a composition and I don’t know whether it is grammatically correct:

He is so cute, I thought.

Firstly, since the whole composition is in past tense, is it correct to use “is” here?

Secondly, do thoughts need to be in quotation marks, i.e.

“He is so cute,” I thought.

  • Also this: english.stackexchange.com/q/21835/191178
    – Laurel
    Commented Jul 25, 2020 at 10:26
  • The 'straight' (involving actual speech) quote structure is well known: "He is so cute," I said. (For completeness, some say that the comma is not absolutely essential nowadays, especially with an inverted speech tag such as << [,] said John. >> And there are different conventions preferring comma placement (if the comma is opted for) within or outside the inverted commas. With thoughts, inverted commas are optional. Some prefer italics << He is so cute I thought. >> and the comma again considered optional by some. However, some form of offsetting is needed, at least comma or italics. Commented Jul 25, 2020 at 11:27