جَاءَ هَؤُلَاءِ. — These people came.
Hāʾulāʾi: demonstrative, built on kasra, in nominative position as subject.
رَأَيْتُ هَؤُلَاءِ. — I saw these people.
Hāʾulāʾi: in accusative position as object.
مَرَرْتُ بِهَؤُلَاءِ. — I passed by these people.
After bi-, it is in genitive position.
Its ending remains unchanged in all three.