Heidi clearly saw the reaction she recieved be being so close to Tracey. She absolutely loved the responses she could coax out of the girl. They were always adorable.
About to lean in for a kiss to try and avert Tracey's concerns for her health, she stopped when Tracey continued talking. She heqard the strain on the 'lie down' part of the words and figured her girlfriend was up to something and she wasn't going to stop her. She hoped it would be enjoyable. "Okay." she gave in and laced her fingers with Tracey's as they walked.
Walking a step or so behind Tracey, she didn't know yet where the Slytherin was taking her, wondering if it was the Room of Requirements, since that seemed to be the only place that they could go.