Should "each" be followed by a singular or plural possessive? [duplicate]

If a possessive noun, which is plural, is preceded by "each", then should it use the singular or plural possessive form?

For example, which of the following is correct?

  • spend time in each other's presence
  • spend time in each others' presence

Solution 1:

Each other is singular, so the correct possessive is each other's.

Edit:
I found some controversy on this on the web because each other implies that there are multiple people involved, hence people think it is plural and should be written each others'. This, however, is wrong as each is always singular.