Symmetric pairs consist of a complex simple Lie algebra and a subalgebra fixed by an involution. Passing to enveloping algebras, the latter becomes a Hopf subalgebra. Hence, its category of representations is naturally a monoidal category. The quantum analogue of this concept is that of a quantum symmetric pair. In the quantum setting, the subalgebra, called an iquantum enveloping algebra, is not a Hopf subalgebra. Rather, it is a coideal subalgebra. This means that the category of representations of the iquantum enveloping algebra is not monoidal. Instead, it is a module category over the category of representations of the larger quantum enveloping algebra. In this talk, we will explore the representation theory of iquantum enveloping algebras from the point of view of diagrammatic interpolating categories. This is joint work with Hadi Salmasian and Yaolong Shen.