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Two independent pairs of roles apply to every swap.

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Taker and maker (who asked, who answered)

The legs are named from the maker’s side: Both roles use the same endpoints for negotiation and settlement. One API key can hold both scopes.

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Initiator and counterparty (who holds the secret)

The initiator is not chosen by who asked. It is chosen by the chains: whoever funds the leg on the chain with the longer safe timelock is the initiator. On a tie, the taker (leg b) is the initiator. See HTLC and timelocks. Example: a taker selling BTC for Sepolia USDT funds the Bitcoin leg (24 h), so the taker is the initiator.
You learn whether you are the initiator from the thread: the server refuses the initiator’s accept without a hashlock. Treat any refusal that asks for a hashlock as “you are the initiator”.

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The keeper

The keeper is a server process. It can submit claim and refund calls on chains where those calls are permissionless, so a leg settles even if its party is offline. It never receives user principal: a claim pays the leg’s fixed recipient, a refund pays the funder. See Non-custodial guarantees.