If they won't comply with your verbal request to move (most won't), they can be difficult to budge and don't take kindly to being dislodged from their warm and comfortable spot.
My cat has two cat beds, one of which is on my bed, and many comfy places to sit; yet, she will often commandeer my side of the bed or my favorite easy chair. Sometimes I let her remain in my easy chair because I don't want or really need to disturb her. I draw the line at my side of the bed. Luckily, Calliope and I, after 16 years together, communicate quite well. I usually only have to say, "You're going to have to move over," and she'll let me know she objects with some indignant meowing, but will then move to her side of the bed or to the back of the chair. Usually.
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