When trying to determine if an ISTP (Introverted, Sensing, Thinking, Perceiving) likes you romantically, it's important to consider their unique personality traits and behaviors. ISTPs are known for being reserved and private individuals who prefer to observe and analyze their surroundings. They may not express their feelings openly, making it challenging to decipher their romantic interest. However, there are several signs that can indicate an ISTP's attraction towards you:

1. Increased attention: ISTPs typically have a practical and logical approach to life, but if they develop romantic feelings for someone, they may start paying more attention to that person. They might listen intently to your conversations, remember small details about you, or show genuine interest in your hobbies and activities.

2. Physical proximity: ISTPs are not usually touchy-feely individuals, but if they like you romantically, they may find subtle ways to be physically close to you. They might sit or stand closer than usual, initiate casual physical contact like brushing against your arm, or find excuses to be in your vicinity.

3. Active participation: ISTPs are action-oriented and enjoy engaging in hands-on activities. If they like you, they may actively seek opportunities to spend time with you, especially in activities they enjoy. They might invite you to join them in their hobbies, adventures, or projects, as they appreciate sharing experiences with someone they are interested in.

4. Practical gestures: ISTPs are known for their practicality and problem-solving skills. If they have romantic feelings for you, they may express it through practical gestures rather than grand romantic gestures. They might offer to help you with tasks, fix things for you, or provide practical solutions to your problems.

5. Increased teasing: ISTPs often use humor and playful teasing as a way to interact with others. If they like you, they may engage in more teasing or playful banter with you. This is their way of showing interest and creating a connection, as they feel more comfortable expressing themselves through humor.

6. Protective behavior: ISTPs have a natural inclination to protect and provide for those they care about. If they have romantic feelings for you, they may display protective behavior, such as offering assistance when you're in need, ensuring your safety, or standing up for you when necessary.

7. Vulnerability: ISTPs are generally guarded individuals who find it challenging to express their emotions. However, if they trust you and feel a romantic connection, they may gradually open up and share more personal thoughts and feelings. This can be a significant sign that they are interested in you romantically.

It's important to note that every individual is unique, and these signs may vary from person to person. Additionally, ISTPs value their independence and may take their time to fully commit to a romantic relationship. Therefore, it's crucial to be patient and allow them the space they need to process their feelings and make a decision.