Answer:
Megan's mother looked after Andy during those months with something close to genuine fondness- not pity, not obligation-as though Andy had become the son she always wanted.
Explanation.
The start of a sentence should be capitalized- the only capitalized word at the start of a phrase is 'Megan's'.
Megan's mother looked after Andy PREP
during those months.
The base sentence uses with as the preposition so-
Megan's mother looked after Andy with something close to genuine fondness-
the (-) indicates an appositive so you need another - to close it.
Megan's mother looked after Andy with something close to genuine fondness- not pity, not obligation-
Original sentence uses as.
Megan's mother looked after Andy with something close to genuine fondness- not pity, not obligation-as though Andy had become the son
Fit in the last phrase and close the sentence with a period.
Megan's mother looked after Andy during those months with something close to genuine fondness- not pity, not obligation-as though Andy had become the son she always wanted.