I've been using italics for thoughts (and emphasis).
One way to represent thoughts and internals --this is probably the most common way -- is to use Italics to show
Internal Monologue only. The rest of what's going on inside the POV character's head is in regular type.
For example:
(Underlines represent what will be printed as Italics.)
************
"I'm packing. I'm packing. Ok." She picked out half a dozen stakes, testing the points one by one before she dropped them in the knapsack.
Never depend on a blunt stake.
"Hurry." John-Tom clicked a metal case closed.
That's the knives. Good. She didn't feel reassured to any extent. But then, she didn't expect to live through this. "The car's gassed up."
"You checked the oil and water?"
"And the air. And the tires."
Fear put cold hands on her shoulder and giggled in her ear. None of these damn careful preparations mattered.
I'm going to get eaten by were-alligators. Hell of a way to die.
****************
In this example, the Italics are for the 'virtual 'conversation', the one-sided conversation, the POV character is holding with herself.
They're not for the rest of her thoughts.
In Vampire/Amazon, there are two flashbacks. I first thought to make these extended thoughts, which would also switch the point of view from third to first. One of them is even with one characters other introspective thoughts.
What it is . . .
a flashback is not Internal Monologue. And only Internal Monologue -- generally -- gets Italics.
So when somebody puts a flashback in Italics it's not to present Internal Monologue or because this is the POV character's thoughts. It is simply to set the passage off from the main text.
A dream sequence or a letter is also sometimes put in Italics.
You are right to worry about long passages in Italics. This annoys the hell out of readers.
I'm thinking about starting the flashback scenes with one "hey, I'm thinking" line, then a white space before normal text.
There are many techniques to sliding into and out of flashbacks. One likes to do it without disrupting the reader's immersion in the story.
This is probably the most basic way to 'flashback'. It's the 'follow an object in' method.
************
Mary stacked the dishes and carried them from the table to the sink and began to wash them.
Her mother's dishes. They had roses round the rim and gilding, mostly worn off. She must have washed these plates a thousand times.
She remembered . . . They were in her stepfather's kitchen. The big cast iron sink was so high she had to use a box to stand on to get to the spigot and so deep she couldn't reach all the way down to the bottom to pick up dishes. Mama had to hand them to her.
"Only a few more." Mama had looked tired. She always looked tired. A dozen strands of her hair fell down over her face and she didn't push them back. "Then we're done."
"Are we having pie?"
"Not tonight, love." Mama didn't meet her eyes. They both knew there was pie. Cherry pie. Mr. Duggins and his sons would eat it all. There wouldn't be a bite left for her.
***************
This basic flashback transition sequence is:
(a) take an object in the present time. (in this case, the plate.)
(b) let it link to the past.
(c)
Say something that shows this is a memory, (i.e. 'she remembered', 'it came to her clearly', 'she could almost see', 'back in the old days', 'once, long ago,' etc.)
(d) Begin in past perfect tense.
(e) Slide into simple past tense.
One can leave a flashback gradually by doing the same steps in opposite order. Slip from simple past tense to past perfect and follow an object or realization or whatever back to the realtime of the story.
Alternately, you can do a sudden interruption.
("Honey? Want me to finish those?" John had come up behind her. She looked up from the sink . . . etc.)
And I'm sort of wondering if I should go into first person for the flashbacks or back off to a third person P.O.V.
You can make the POV character into a kind of narrator, speaking directly to the reader.
You can do the flashback in Omniscient Narrator.
You have lots of choices.
Flashbacking isn't an obvious or easy technique. It needs a little study. Best way, I think, is to keep an eye out for flashbacks in your reading. Ask your friends to do the same. Then mark the transitions and see how the masters do it.
