Spell check doesn’t necessarily catch words that are spelled correctly but chosen incorrectly. Here’s a list of some of the most common I’ve found in my editing experience. (Written in a certain vein, because vampires need proper grammar too.)
accept/except:
Of course I’ll accept (agree with, allow) your tongue at my throat. After the summer drought, I thirst for everything except (excluding, omitting) the thought of your departure.
affect/effect:
What will be the effect (result) of this dry, hot summer? More than these lost barley rows, the drought will affect (influence/cause a response) the substance of my blood, my ability to quench your constant need.
(Usually, “effect” is the noun, and “affect” is the verb; however, “effect” is sometimes used as a verb, as in, The drought effected (to bring about) great change in my body. And sometimes “affect” can be used as a noun, as in, He affected (assumed) a wry humor that belied his concern at the loss of blood.)
capitol/capital:
On the stairs of the old capitol (the building only), we waited for the sun to rise over the state’s capital (town or city holding government). For a moment, we forgot our impending death, content with the joy of last night’s capital (financial assets) blood gains.
ensure/insure:
If she were to acquiesce to his demand, Emily would first ensure (make certain) the well-being of her family. She would insist the vampire insure (plan money payment for loss) her against the loss of her royal blood.
farther/further:
I will not go one step farther (physical distance) if you speak any further (abstract quantity) about my own lust being greater than yours. We are the same.
its/it’s:
It’s (it is) the memory of sun on new green leaves and its (possessive/belonging to) bright heat on the farmhouse porch that keeps me at the window past dawn’s torturous waking.
lightning/lightening:
Although the heavy storm clouds were lightening (lesser in weight) beyond his black cape blowing, the horizon sparked with lightning (electrical force).
principle/principal:
The principal (main, foremost) goal of our midnight meeting was to establish the principles (rule, truth) by which our passion could be sated—without offending the now sterile principal (chief person, head) of our vampire coven.
proceed/precede:
The wedding party will precede (to go or come before) the vampire bride, who will then proceed (to go on or move forward) into the reception hall to taste the guests.
stationary/stationery:
Before composing my letters of consolation on this vibrant green stationery (writing paper), I must find a table more stationary (motionless, unmoving) than these skeletal remains of my month-long feast.
their/there/they’re:
They’re (they are) forever dancing up there (in a place), all these black and starless nights, in their (possessive, belonging to) translucent skin and ghostly gauze dress.
who’s/whose:
I hope that the vampire who’s (who is) dancing above my ceiling knows whose (possessive, belonging to) black heels and heart have danced there once too.
you’re/your:
With all these rules you devise for self-protection, you’re (you are) still left no choice but to follow what most ignites your (possessive, belonging to you) absolute and undeniable need.