How does a mix between Proof of Work/Stake work? (Peercoin)
I am not an expert on Peercoin, but a hybrid consensus model of Proof-of-work (PoW) and Proof-of-Stake (PoS) already exists with Decred (DCR), and I know a couple of things about it.

Differences between PoW &amp; PoS:


PoW needs miners who use mining hardware to find blocks and verify new  transactions sent to the network.
PoS needs stakeholders who stake/lock up coins to validate blocks already mined by the miners. The stakers can vote to invalidate blocks created unfavourable PoW-mining behaviour, like mining empty blocks.


Similarities between PoW &amp; Pos:


Both PoW- and PoS-miners have voting power to create consensus of code changes on the blockchain.
Both PoW- and PoS-miners gain block rewards or a percentage of the reward.
Both PoW- and PoS-miners can use mining pools for a more consistent and stable flow of funds.
Both PoW- and PoS-mining are methods of making the network more secure against attacks.


Decred PoS ticket system (simplified):


Tickets have a price. e.g: 100 DCR. (see https://dcrstats.com for current ticket price.) This amount varies depending on how many tickets are are bought in total on the network. When you buy a ticket, the amount is staked/locked up and is still in your ownership.
After a period of time (from 28 days to 142 days), if the ticket has successfully vote, then the DCR are sent back to your wallet + a portion of the block reward. This reward amount varies depends on many factors, and can be everything from 10-30% reward per year.
Decred is developing ticket-splitting pools so stakers wouldn't need the whole ticket price to begin staking.


I looked up PeerCoin (PPC) Staking/Minting


Staking PeerCoin is done by having the coins stay in your synced wallet. This means you are running a PeerCoin node, and this will reward you ~1% per year. This is called 'Minting'. (Read https://peercoin.net/minting for more info.) I didn't find many technical details in the Whitepaper of PPC.


I hope this clarifies some things about PoW/PoS Hybrid Consensus System, and I'm sorry I can't provide more specific info about PeerCoin.