One goal of modern astrophysics is to understand the formation and evolution of galaxies. Cosmological zoom-in simulations are a tool we can use to test our theories about galaxy formation. Using the FIRE-2 (Feedback in Realistic Environments) high-resolution simulations that track star, gas, and dark matter particles over the course of billions of years, I examine Milky Way-like galaxies. I study stars in both isolated and paired galaxies and compare the dynamics and properties of their stars. In my study, I categorize stars into three age groups, each measured in billions of years: Young (0-5 Gyr), Intermediate (5-10 Gyr), and Old (10+ Gyr). I am focused on studying the most ancient stars in these galaxies, located within a cylindrical volume centered on the galaxy's center and along the z-axis. This volume has a radius of 1 kiloparsec and a total length of 20 kiloparsecs, with 10 kiloparsecs both above and below the center. This volume was chosen to limit the number of disk stars selected and primarily study stars with halo-like orbits. From this volume, I randomly selected 100,000 stars per age bin of stars to study. I have found from these simulations that old stars are more likely to have been formed ex-situ than younger stars. The parameter for ex-situ formation in my research is that a star formed more than 20 kiloparsecs away from where the center of the galaxy is at the snapshot moment. The data suggests that a major component of early growth in Milky Way-like galaxies is hierarchical formation or accretion. The calculated ratios of ex-situ to in-situ stars suggest that early accretion was supplemented by secular growth. I have also found that old stars are largely halo stars as well as disk stars. Disk stars follow the main rotation of stars in the most populated region of the galaxies, while halo stars tend to follow more irregular orbital paths. The number of old stars with negative angular momentum compared to young stars, along with the frequency of properties like z max, apocenter, and pericenter further suggests that many stars are accreted during early growth in Milky Way-like galaxies. This can be compared to the Milky Way, and based on the orbits of stars in our galaxy and their properties we can predict their ages, and vice versa. Ultimately, these predictions allow us to better understand the dynamics of stars within the inner halo of the Milky Way Galaxy. This research will allow us to make predictions about the ages, dynamics, and distribution of stars, as well as for the Milky Way as a whole. The more we can learn about our own galaxy, the more we will understand the dynamics of the universe that we are a part of.